CBSE Solutions For Class 3 Maths Chapter 3 Double Century

CBSE Notes For Class 3 Maths Mela Chapter 3 Double Century

The Story Of Our Numbers

Tens of thousands of years ago, people started counting. They wanted to keep records of their things. So they made marks on the walls of caves and on the barks of trees.

Over time, they kept records of their things by making groups of 5, 10, 20, and 60.

Thousands of years ago, the ancient Indians created a method for
writing any number, however large, using only ten symbols: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9. It was one of the most ingenious and creative inventions in human history. It made possible the invention of TVs, computers, mobile phones, and more. This method of writing numbers is now used everywhere in every country in the world.

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A very important part of this invention was the introduction and use of the symbol “0” to mean “nothing”. It is the number 0 that made this system of writing numerals work!

Over the next few months, we will learn how to write all numbers, however large, using just these ten symbols.

Let Us Do

Question 1. Look at the picture. Estimate and write the number of each of the following objects.

Double Century The number of each of the following objects

  1. Oranges: _________
  2. Bangles: _________
  3. Laddoos: _________
  4. Barfi: _________
  5. Bindis: _________
  6. Bananas: _________

Answer:

Let Us Play

Fill in the missing numbers on the board.

Double Century Numbers on the board

Answer the following on the basis of the Snakes and Ladders board:

  1. Which number will you reach if you take the ladder from 13?
  2. If you are on the snake at number 25, which number will you reach?
  3. You are standing on 96. Which number on the die will take you to the snake’s mouth?
  4. Show the number written on the tail of the longest snake using bundles and loose sticks. _____

Let Us Think

Double Century I am a talking pot

These beads are also 100 in number.

Let Us Do

Question 1. Fill in the blanks.

Double Century Number sentance

Bholu made 100 by jumping on 65 and then 35 more.

Double Century Bholu made 100 by jumping

Question 2. Use matchstick bundles and a glad to make 100 in different ways. Fill in the table below.

Double Century A ginladi to make 100 in different ways

Question 3. Write numbers in the blank spaces inside the flower petals so that the numbers in each petal add up to 100.

Double Century The flower petals

Let Us Explore

How many are 100?

Question 1. Open a full box of matchsticks.

  • Estimate the number of matchsticks in the box: ________
  • Count the number of matchsticks in the box: _________
  • How close was your estimate?
  • How many boxes of matchsticks will get the total close to 100 matchsticks? ________ boxes.

Double Century Full box of matchsticks

Question 2. Take a handful of seeds like kidney beans, chickpeas, etc.

  • Estimate the number of seeds you have in your hand: ________
  • Count the number of seeds in your hand: _________
  • How many handfuls of seeds will get the total close to 100 seeds? ________ handfuls.

Double Century A handful of seeds like kidney beans

Double Century Numbers beyond 100

Fill in the blank spaces on the number line given at the edge of the page.

Let Us Do

Question 1. Let’s continue making numbers above 100 using matchsticks bundles and loose sticks.

In the table given proxy. identify the bundles and loose sticks and write the corresponding numbers.

Double Century The bundles

Extend the table in your notebook to 150. Do you observe something common in all the numbers?

Match the number with the correct bundles and loose sticks.

Double Century Bundles and loose sticks

Oh! Talking Pot is back. It will say one more than whatever you say.

Double Century Talking pot is back

Fill in the blank spaces on the number line.

Double Century The blank spaces on the number line

Show the following numbers on the number line below.

  1. Place an arrow on 125.
  2. Make a tree on 112.
  3. Make a smiley on 149.
  4. Put a cross on 137.

Double Century The number line below

Let Us Play

Double Century Numbers by clap

Play this game in two teams. One team will show a number using clap, snap, and pat and the other team will guess it. Example: Clap- Snap Snap- Pat Pat Pat means 123 (One hundred and twenty-three).

Let’s now count beyond 150.

Double Century Count beyond 150

Extend this table to 200 in your notebook How much is 200?

Let Us Do At Home

Question 1. Fill a small container like a small bowl with seeds such as kidney beans, chickpeas, etc.

Double Century Small bowl with seeds

Question 2. Look closely at the container to estimate how many seeds are in it. Your Estimate: _______ seeds.

Question 3. Now count and see how close your estimation is to the actual number of seeds. Counted _____ seeds.

Double Century Counted seeds

Question 4. Guess how many times you need to fill the container to get close to 200 seeds. Your guess: _____ time.

Double Century Container to get close to 200 seeds

Write the numbers in order on the stones.

Let Us Do

Jumping Game

Question 1. Draw jumps of 5 on the number line and write the numbers on the number line in the given spaces.

Double Century Jumps of 5 on the number line

Question 2. Continue jumps of 20 and write the missing numbers on the given number line.

Double Century Jumps of 20

Question 3. Fill in the table.

Double Century The table

Question 4. Show at least two different ways of making the following numbers.

  1. Use matchsticks bundles to make 125.
  2. Make 145 using a glade.
  3. Make 170 on a number line.

Question 5. Fill in the empty boxes appropriately.

Double Century The empty boxes

Question 6. Mark the following numbers on the number line.

1. 109, 112, 124, 134, 146

Double Century Number line 146

2. 155, 163, 178, 189, 198

Double Century Number line 198

3. 125, 142, 153, 174, 199

Double Century Number line 199

CBSE Solutions For Class 3 Maths Chapter 1 What’s In A Name?

CBSE Notes For Class 3 Maths Mela Chapter 1 What’s In A Name?

A long long time ago, there was a cowherd family in Tarakeshwar. Every day Deba and Deep took the cows out for grazing. They used to return in the late evening together with all the cows.

One day, Deba asked: How do we know that we have not lost any cows? They did not know how to count.

What's In A Name A long time ago

What could Deba and Deep do?

Their friend gave them an idea: When you go out, make a mark on the wall for each cow that leaves the gate. Then when you come back, strike out one mark from the wall each time a cow re-enters the gate.

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The next day they followed their friend’s idea, and all the marks were struck out when they came back home.

What's In A Name Deba and Deep

Did all the cows come back home?

After a few years, they had many more cows. One day, their wall had this many marks when they left home.

So, they had….cows.

The next day they returned with the cows. They struck out one mark as each cow re-entered the gate. Two marks were still left on the wall but they didn’t see any cows outside. They were worried.

What's In A Name Wall had this many marks

Why were Deba and Deep worried?

How many cows had reached home?

Deba and Deep quickly went to search for the missing cows and found them in a nearby field. They all happily returned home together!

Their friend Hemant had 36 cows and 23 sheep.

Help Hemant keep track of his cows and sheep by making marks like Deba and Deep.

Let Us Do

Question 1. Some animals and birds got together to play a game. They wanted to make 2 teams. They decided that the captain of the first team would be the one with the longest name, i.e., the one with the most letters. The captain of the second team will be the one with the shortest name, i.e., the one with the fewest letters.

What's In a Name Animals

Find out the captains of the 2 teams.

What's In a Name Capatins of the 2 teams

Question 2. Who has a longer name? Discuss.

What's In a Name Longer names

Question 3. Write down the names of some of your friends in the spaces given below and then answer the questions from a to f.

  1. Tick Toy Joy Tick the longest name(s) and cross Toy Joy Cross the shortest name(s).
  2. Write the starting letter of your name. ___________
  3. Count all the name(s) that have the same starting letter as yours. ___________
  4. Which starting letter is the most used? Count the names that begin with it. __________
  5. Count the names with the same ending letter. ________
  6. Write the letters that are not the starting letters of any name. __________.

Question 4. Teji and Jojo are making numbers using these cards.

What's In a Name Teji and Jojo are making numbers

  1. Write your roll number using number cards as shown above. Number cards are given at the end of the book.
    • My roll number is
    • Its number name has letters.
  2. Write some numbers and their number names in your notebook. How many letters does each have?

Let Us Think

What's In a Name Teji and Jojo made the number 56

Let Us Do

Question 1. Write the number(s) between 1 and 99 that have the longest name.

What's In a Name The numbers between 1 and 99 have the longest name

Question 2. Make similar puzzles of your own in your notebook and ask your classmates.

Venkatanarasimharajuvaripeta is the place in India with the longest name. It is located in Andhra Pradesh, close to the border of Tamil Nadu.

What's In a Name Venkatanarasimharajuvaripeta

Ib in Odisha and Od in Gujarat are the places in India with the shortest names.

What's In a Name Ib in Odisha and Od in Gujarat

Teji and Jojo have some picture cards. Teji has put these into two groups like this:

What's In a Name Picture Cards

She has grouped the cards into “those that eat food” and “those that don’t eat food’. Jojo Gas arranged the same cards differently.

What's In a Name Cards

What is common in each of the groups Jojo has made?

Given below are pictures of some household objects.

What's In a Name Some household objects

Write the names of the above objects in the groups given below.

What's In a Name Names of the above objects in two groups

Group the objects given above differently. Write them down in the space below.

What's In a Name Group the objects given above differently

Let us Do

Hair Styles

Mala is going to school. What's In a Name MalaHer mother has combed her hair, What's In a Name Mala's mother Mala has two ponytails. What's In a Name Mala has two ponytails

Look at the children in your class. What's In a Name The children in class

All children comb their hair in different ways. What's In a Name All children Hair in different ways

Look and write down.

What's In a Name Hair style

CBSE Solutions For Class 3 Maths Chapter 4 Vacation With My Nani Maa

CBSE Notes For Class 3 Maths Mela Chapter 4 Vacation With My Nani Maa

Vacation With My Nani Maa

Can you tell me what the trick is?

Let Us Do

Perform the trick on your friends. Write the numbers of hidden seeds in the table below.

Read and Learn More CBSE Solutions For Class 3 Maths

Vacation With My Nani Maa Numbers of hidden seeds in the table

Vacation With My Nani Maa 4 Nandini takes out nani maa's favourite sweet balushahi

7 Balushahi – 5 Balushahi = _________ Balushahi

Chirag got 9 story books for Nani Maa and Nandini got 7 puzzle books for Nani Maa. How many total books did the children get for Nani Maa?

Vacation With My Nani Maa Chirag got 9 story books for nani maa

Let Us Do

Use the tens frame to solve the following.

  1. 6+8 = ________
  2. 5+10 = _________
  3. 9-6 = _______
  4. 18-9 = _________

Vacation With My Nani Maa The tens frame

Let Us Play

Make four sets of number cards with numbers 1 to 10. Shuffle and spread out all cards facing down. Take turns with your friends to open one card at a time. When you open look at your card, and the cards are already opened.

Vacation With My Nani Maa Card game

If any three cards make an addition or a subtraction statement, you can keep all three cards. Else, put it down and opened. For example, Nandini opens 4. Numbers 2 and 6 have already been opened. So Nandini can keep all three cards 2, 4, and 6. The game continues till all cards are opened. Whoever collects the greatest number of cards wins the game.

Vacation With My Nani Maa Nandini nd chirag have got their stamps

Nandini and Chirag have got their stamps to show to their friends and Nani Maa.

How many stamps do they have now?

Nandini, Chirag, and Nani Maa figured out the answer in three different ways using their inlaid:

Vacation With My Nani Maa The answer in three different ways using their ginladi

Let Us Do

Nandini and Chirag have 22 stamps. Nani Maa’s brother gives them his collection of 30 stamps. How many stamps do they have now?

Vacation With My Nani Maa Nandini and chirag gave 22 stamps

They now have 52 stamps. Nandini and Chirag counted and found that they have 37 stamps with faces of famous persons and the remaining with pictures of monuments.

How many stamps with pictures of monuments do they have?

Vacation With My Nani Maa 15 stamps with pictures of monuments

How many more stamps will they need? Figure it out using the number line.

Vacation With My Nani Maa Many more stamps will they need

Let Us Do

Question 1. Solve using a ginaladi.

  1. 34+6
  2. 23+12
  3. 33-5
  4. 42-15

Vacation With My Nani Maa A ginladi

Question 2. A frog is jumping on the ginladi. He is at 7. He wants to jump 10 beads at a time. mark the beads that he will jump on and write the numbers.

Vacation With My Nani Maa A frog s jumping on the ginladi

Question 3. The frog again jumps forward by 10 each time. Mark all the places where the frog will land.

Vacation With My Nani Maa The frog again jumps forward by 10 each time

Question 4. The grasshopper jumps backward by 10 each time. Mark all the beads that the grasshopper will jump on and write numbers.

Vacation With My Nani Maa Thr grasshopper jumps backward by 10 each time

Some ants are carrying big leaves to their homes. They will eat these leaves in the rainy season. Nani Maa can tell how many ants there are without looking under the leaves. Can you also tell me how many ants are under the leaves? Fill in the answers in the boxes provided.

Vacation With My Nani Maa Ants are carrying big leaves to their homes

Question 5. Fill in the tables by jumping as instructed.

Vacation With My Nani Maa Jumping as instructed

Let Us Play

Adding and Subtracting Smartly with the Number Grid

Vacation With My Nani Maa The number grid

Let us play a grid game. Each player takes turns rolling two dice to make a two-digit number and moves the counter by the number they have made. They can choose to move forward or backward. The first to reach a number between 91 and 100 is the winner!

Vacation With My Nani Maa's Nadini is at 23

Question 1. Use the number grid to answer the following. Show your thinking by drawing arrows in the grid.

  1. Nandini is at 45. She gets 34. She will land on ________.
  2. Chirag is at 75. He gets 56. He will land on _________.
  3. Nandini is at 30. She gets 66. She will land on __________.
  4. Chirag is at 89. He gets 63. He will land on ___________.

Vacation With My Nani Maa Arrows in the grid

Magic Sums

Nandini and Chirag find some puzzles that Nani Maa has solved.

Observe the numbers. What do you notice?

Vacation With My Nani Maa Some puzzles

Fill in the boxes below. In each puzzle, all numbers 1-9 are there. The numbers in each row add up to the number in the box on the right. The numbers in each column add up to the number in the box below.

Vacation With My Nani Maa Number in the box

Add the numbers in the blue boxes and the numbers in the red boxes in each of the puzzles. What do you find?

Nani Maa was doing something in the newspaper. Nandini and Chirag looked into what she was doing.

Vacation With My Nani Maa Magical about this square

Magic magic magic!!!
With numbers1 to 9
Add the numbers in a line
From left to right
And from top to bottom
Didyoufind the magic?
Now, try from right to left
And from bottom to top
Isn’t it magical?
There is something more,
something more
Add the numbers on the diagonal
Isn’t it magical?

Fill in the blanks to complete the magic square

Vacation With My Nani Maa Magic with number 1 to 9

Nandini and Chirag went to their Nani Maa’s field. Nani Maa has two fields.

Vacation With My Nani Maa Nandini and chirag went to their nani maa's field

Nani Maa has plucked 25 red radishes and 36 white radishes. How many total radishes has she plucked?

Nandini starts by drawing the problem on the ground.

Vacation With My Nani Maa Total number of radish

We need to add 25 and 36 to find the total number of radishes.

Vacation With My Nani Maa Number line

Nani Man puts tomatoes and carrots in a box and writes 100 on it.

Vacation With My Nani Maa Put tomatoes and carrots in a box

Circle the bundle of sticks that shows the correct number of carrots.

Vacation With My Nani Maa The bundle of sticks

Solve the above problem on the number line.

Vacation With My Nani Maa The number line.

Nani Maa asks Nandini and Chirag to pluck the ripe apples. Woho! so many of them.

Vacation With My Nani Maa 50 Pluck the ripe apples

Try finding out the answer on the number line below.

Vacation With My Nani Maa Number line below

Who collected more, Nandini or Chirag? How much more?

Chirag draws a box diagram for the problem.

Vacation With My Nani Maa A Box diagram

Solve the following problems by first drawing the box diagrams, Use matchstick bundles or a number line to find the answer.

  1. Babli didi sold 34 books on Monday and 45 books on Tuesday. How many books did she sell in the two days? How many more did she sell on Tuesday than on Monday?
  2. In a cricket match at Rosary School, Team Red made 56 runs before lunch and 65 runs after lunch. How many total runs did they make?
  3. Rama sells vadas in the school canteen. She has sold 39 vadas on the first day. She sold 12 more the next day. How many vadas did she sell in these two days?
  4. Gehu brings 56 plants for her terrace garden. Some plants dried up. She is left with 29 plants. How many plants dried up?
  5. Choose two numbers. Make a word problem using the two numbers. Share it with your classmates.

Let Us Play

This game is to be played between two children. The first player should say a number between 1 and 10. The second player adds a number between 1 and 10 to the first player’s number. The first player again adds a number between 1 and 10 to the previous sum. The player to reach 100 first is the winner. An example is given here:

Vacation With My Nani Maa Game is to be played between two children

Player 1 wins this round!

Play this game with your friends.

Let Uo Do

Question 1. Estimate the answer and say if it will be more or less than 100. Match with the correct one.

Vacation With My Nani Maa More or less than 100

Question 2. Solve the above problems using a number line. Write the answer next to the problem.

Vacation With My Nani Maa Problems using number line

CBSE Solutions For Class 3 Maths Chapter 2 Toy Joy

CBSE Notes For Class 3 Maths Chapter 2 Toy Joy

Some children are making animal and bird faces on old boxes, cans, and paper.

Toy Joy Childrens are making animals

Let Us Do

Use old boxes (cubes and cuboids) and bottles (cylinders) to do craft work. Draw faces on them. What did you draw on their faces?

Read and Learn More CBSE Solutions For Class 3 Maths

Toy Joy Old boxes

  • Jaya is building a rocket with her shapes. What shapes has she used?
  • How many of each?

Cube: _________ Cuboid: _________

Cone: _________ Cylinder: _________

Toy Joy Jaya is building a rocket with her shapes

  • What shape is between the red cuboid and the yellow cuboid?
  • What shape is on the top of the orange cylinder?
  • What shape is under the pink cone?

Toy Joy Red and yellow cubiods

Collect objects to make a house. Name the shapes and talk about their faces and edges. Which are straight and which are curved? Also, describe how the shapes have been arranged. What part of the shapes can you see from a distance?

Toy Joy Devika went to a shop and bought a toy engine

Devika went to a shop and bought a toy engine.

Here is Devika’s toy engine. It has many parts. Count and fill.

______ red cylinder(s) _________ yellow cone(s)

______ grey cuboid(s) _________ blue cube(s)

Let Us Discuss

Here are some more toys from the toy shop. They are made up of different shapes.

What shapes are used in these toys?

Toy Joy Shapes are used in these toys

Jaya made some houses using different shapes.

Try to build such houses, towers, rockets, etc. using different shapes available around you.

Toy Joy To build such houses

Note that a cube is a special type of cuboid.

Let Us Play

Construct And Describe

Ask students to sit in groups of four or five. In each group, one student selects any three shapes and puts them together. The student, then describes the sequence of construction and the other students have to build the same without seeing the original one. Let children take turns and play the game in the group.

Toy Joy Select any three shapes and put them together

Example

The cylinder is on top of the cuboid. The cone is on top of the cylinder.

Let Us Do

Question 1. Can you find these shapes in the classroom? Fill in the table with their names.

Toy Joy Shapes in the classroom

  1. Name the shape that you find the most. ________
  2. Name the shape that you find the least. ________
  3. Name the objects that are made up of more than one shape. _______

Question 2. Look at these shapes and answer the following questions.

  • Circle Toy Joy Circle the cubes.
  • Put a tick Toy Joy Tick against the shapes that are cones.
  • Put a cross Toy Joy Cross against the shapes that are cones.
  • Put a box Toy Joy A box around the cuboids.

Toy Joy Shapes

Question 3. Name the shapes

  • with no edges. __________
  • with only flat faces. _________
  • with only curved faces. ________
  • with both straight and curved edges. _________
  • with both flat and curved faces. _________

Question 4. Which shapes can you build?

Toy Joy Shapes can be build

Question 5. Try to make these shapes using cubes.

Toy Joy Shapes using cubes

Let Us Play

There is a game along the border of this page. Roll the die and move the counter to the next picture associated with the number on the die (if possible without crossing the “Finish” square) and play the game with your friends. The one who reaches the finish mark first wins the game.

Toy Joy Game

Question 6. In what ways are these shapes the same? In What ways are they different?

Toy Joy Shapes the same ways are they different

Question 7. Look at a die. The faces have 1 to 6 dots. What number is on:

  • The face opposite number 1? __________
  • The face opposite number 2? __________
  • The face opposite number 3? __________
  • What pattern do you notice? ___________

Toy Joy A die

Question 8. In what order is this model built?

Toy Joy Model built

Toy Joy Cubes are used to make this shape

Question 9. In how many different ways can you join 3 cubes? try and see.

Toy Joy Many different ways can you join 3 cubes

Question 10. Name the shapes used in these models. Describe how the shapes are arranged to make them.

Toy Joy The shapes used in these models

Question 11. Use six dice to make the following shapes:

  1. A Cuboid
  2. A tower
  3. Any other shape of your choice

NCERT Solutions For Class 10 History Chapter 4 The Making Of A Global World

Chapter 4 The Making Of A Global World Important Dateline

15th CE: The Silk Route still existed that linked vast regions of Asia and Asia with Europe and North America.

1730s: Coming up of Factories in England

1882-1914: The World was transforming very rapidly.

19th century: Corn Law in England

1854: The first modern cotton mill was set up in England.

1874: The first spinning mill was set up in Bengal

1914-18: First World War

1920s: Mass production of cars by Henry Ford.

1920s: Strong Rapid increase in the US economy.

1923: The USA resourced exporting capital to the rest of the world and became the largest overseas lender.

1929: Beginning of Great Depression in the USA

1929-34: Period of Great Depression

1939-1945: The period of Second World War.

1941: German attack on Russia

1944: Bretton Woods Conference

1949: Communist Rule in China.

NCERT Solutions For Class 10 Social Science History Chapter 4 The Making Of A Global World

Chapter 4 The Making Of A Global World Important Concepts And Terms

Dissenter: One who refuses to accept established beliefs and practices.

Indentured Labour: A bonded labourer under contract to work for an employer for a specific amount of time, to pay off his passage to a new country or home.

Tariff: Tax imposed on a country’s imports from the rest of the world. Tariffs are levied at the point of entry, i.e., at the border or the airport.

Exchange Rates: They link national currencies for purposes of international trade. There are broadly two kinds of exchange rates: fixed exchange rate and floating exchange rate.

Fixed Exchange Rates: When exchange rates are fixed and governments intervene to prevent movements in them.

Flexible or Floating Exchange Rates: These rates fluctuate depending on the demand and supply of currencies in foreign exchange markets, in principle without interference by governments.

Cowries or Seashells, are used as a form of currency.

MNCs: Multinational Corporations are large companies that operate in several countries at the same time.

Chapter 4 The Making Of A Global World Ncert Textbook Exercises

Question 1. Give two examples of different types of global exchanges which took place before the seventeenth century, choosing one example from Asia and one from America.

Answer:

Examples of different types of global exchanges which took place before the seventeenth century:

  1. Textiles, spices and Chinese pottery were exchanged by China, India and Southeast Asia in return for gold and silver from Europe.
  2. Gold and foods such as potatoes, soya, groundnuts, tomatoes and chillies were first exported from America to Europe.

Question 2. Explain how the global transfer of disease in the pre-modern world helped in the colonisation of America.

Answer:

The global transfer of disease in the pre-modern world helped in the colonisation of America because the native American Indians were not immune to the diseases that the settlers and the colonisers brought with them.

The Europeans were more or less immune to smallpox, but the native Americans, having been cut off from the rest of the world for millions of years, had no defence against it.

These germs killed and wiped out whole communities, paving the way for foreign domination. Weapons and soldiers could be destroyed or captured, but diseases could not be fought against.

Question 3. Write a note to explain the effects of the following:

  1. The British government’s decision to abolish the Corn Laws.
  2. The coming of rinderpest to Africa.
  3. The death of men of working age in Europe because of the World War.
  4. The Great Depression on the Indian economy.
  5. The decision of MNCs to relocate production to Asian countries.

Answer:

  1. The British government’s decision to abolish the Corn Laws resulted in losses for the agricultural sector, but progress in the industrial sector.
    • Food began to be imported more cheaply into Britain, and thousands of workers involved in cultivation became unemployed.
    • However, consumption increased and the industrial sector grew, with more workers being available in cities than in rural areas.
  2. The coming of rinderpest to Africa caused a loss of livelihood for countless Africans.
    • Using this situation to their advantage, colonising nations conquered and subdued Africa by monopolising scarce cattle resources to force the Africans into the labour market.
  3. The death of men of working age in Europe because of the World War, reduced the able-bodied workforce in Europe, leading to a steady decline in household incomes and a consequent struggle to meet the living expenditure by families whose men were handicapped or killed.
  4. The Great Depression had a major impact on the Indian economy. Between 1928 and 1934, it reduced Indian imports and exports by nearly half.
    • Wheat prices too fell by 50% during this time. More than the urban areas, the agricultural sector (which dominated livelihoods in rural lands) was badly hit by the Great Depression.
  5. The decision of the MNCs to relocate production to Asian countries led to a stimulation of world trade and capital flows.
    • This relocation was on account of low-cost structure and lower wages in Asian countries. It also benefited the Asian nations because employment increased, and this resulted in quick economic transformation as well.

Question 4. Write two examples from history to show the impact of technology on food availability.

Answer:

The impact of technology on food availability was manifold in the late nineteenth century.

Faster railways, lighter wagons and larger ships helped transport food more cheaply and quickly from production units to even faraway markets.

Also, refrigerated ships helped transport perishable foods such as meat, butter and eggs over long distances.

Question 5. What is meant by the Bretton Woods Agreement?

Answer:

The Bretton Woods Agreement was finalised in July 1944 at Bretton Woods in New Hampshire, USA.

It established the International Monetary Fund (IMF) and the World Bank to preserve global economic stability and full employment in the industrial world.

These institutions also dealt with external surpluses and deficits of member nations and financed post-war reconstructions.

Question 6. Imagine that you are an indentured Indian labourer in the Caribbean. Drawing from the details in this chapter, write a letter to your family describing your life and feelings.

Answer:

Indentured Indian labourers in the Caribbean – facts signed a contract stating that they would return to India after working for five years at a plantation.

Belonged to eastern Uttar Pradesh, Bihar, central India and the dry districts of Tamil Nadu; migrants took up the overseas jobs hoping to escape poverty and oppression in their home villages.

Migrants were not even informed about the long sea voyages, and some unwilling ones were abducted as well; also known as “the new system of slavery”.

Harsh living and working conditions; few legal rights; many escaped into the wilds; some developed new art forms for expression; some returned home after the contract period, while others stayed on.

Question 7. Explain the three types of movements or flows within international economic exchange. Find one example of each type of flow which involved India and Indians, and write a short account of it.

Answer:

The three types of movements or flows within the international economic exchange are the flow of trade, the flow of labour and the flow of capital.

These can be explained as the trade in agricultural products, migration of labour, and financial loans to and from other nations.

India was a hub of trade in the pre-modern world, and it exported textiles and spices in return for gold and silver from Europe.

Many different foods such as potatoes, soya, groundnuts, maize, tomatoes, chillies and sweet potatoes came to India from America after Columbus discovered it.

In the field of labour, indentured labour was provided for mines, plantations and factories abroad, in huge numbers, in the nineteenth century.

This was an instrument of colonial domination by the British. Lastly, Britain took generous loans from the USA to finance the World War. Since India was an English colony, the impact of these loan debts was felt in India too.

The British government increased taxes, and interest rates, and lowered the prices of products it bought from the colony. Indirectly, but strongly, this affected the Indian economy and people.

Question 8. Explain the causes of the Great Depression.

Answer:

The Great Depression was a result of many different factors. The post-war global economy was weak. Also, agricultural over-production proved to be a nuisance, which was made worse by falling food grain prices.

To counter this, farmers began to increase production and bring even more produce to the markets to maintain their annual incomes.

This led to such a glut of food grains that prices plummeted further and farm produce was left to rot. Most countries took loans from the US, but American overseas lenders were worried about the same.

When they decreased the amount of loans, the countries economically dependent on the US loans faced an acute crisis. In Europe, this led to the failure of major banks and currencies such as the British pound sterling.

In a bid to protect the American economy, the USA doubled import duties. This worsened the world trade scenario. All these factors contributed to the Great Depression.

It affected the USA the worst on account of its being a global loan provider and the biggest industrial nation.

Question 9. Explain what is referred to as the G-77 countries. In what ways can G-77 be seen as a reaction to the activities of the Bretton Woods twins?

Answer:

G-77 countries is an abbreviation for the group of 77 countries that demanded a new International Economic Order (NIEO).

A system that would give them real control over their natural resources, without being victims of neo-colonialism, i.e., a new form of colonialism in trade practised by the former colonial powers.

The G-77 can be seen as a reaction to the activities of the Bretton Woods twins (the International Monetary Fund and the World Bank).

Because these two institutions were designed to meet the financial needs of industrial and developed countries and did nothing for the economic growth of the former colonies and developing nations.

Chapter 4 The Making Of A Global World Short Questions And Answers

Question 1. Why were Europeans attracted to Africa in the late nineteenth century? Mention any three reasons.

Answer:

  1. Africa had vast resources of land and minerals. Its population was very small and land was abundant.
  2. Europeans were hoping to establish plantations and mines to produce crops and minerals for export to Europe. They faced a shortage of labour willing to work for wages. However, they used many methods like heavy taxes to recruit and retain labour.
  3. In Africa, the Industrial Revolution did not take place. Also, African countries were militantly weak and backward.

Read and Learn More Class 10 Social Science Solutions

Question 2. What were the advantages of the invention of refrigerated ships?

Answer:

  1. Refrigerated ships reduced the shipping cost and lowered meat prices in Europe.
  2. The poor in Europe could now consume a more varied diet.
  3. To the earlier, monotony of bread and potatoes many, not all, could add meat, butter or egg.
  4. Better living conditions promoted social peace within the country and support for imperialism abroad.

Question 3. State three examples to show that the world changed with the discovery of new sea routes to America.
Or
State three examples to show that the pre-modern world changed with the discovery of new sea routes to America.

Answer:

  1. Many of our common foods such as potatoes, soya, groundnuts, maize, tomatoes, chillies, sweet potatoes, and so on were introduced to Europe from America. These crops made a difference between life and death. The poor began to eat better and live longer in England with the introduction of potatoes.
  2. Precious metals, particularly silver, from mines located in present-day Peru and Mexico also enhanced Europe’s wealth and financed its trade with Asia.
  3. It encouraged the slave trade. European traders captured slaves in Africa and took them to America, where they worked on plantations. Europe became the centre of world trade.
  4. Religious dissenters were persecuted in Europe. Thousands therefore fled Europe for America.
  5. Diseases like smallpox, germs of which were carried by Europeans to America decimated the whole community who had no immunity to it.

Question 4. What was the importance of the Indian trade for the British?

Answer:

  1. Trade surplus: Britain had a trade surplus with India. Britain used this surplus to balance its trade deficit with other countries.
  2. Home charges: Britain’s trade surplus in India also helped to pay the so-called home charges that included private remittance homes by British officials and traders, interest payments on India’s external debt and pensions of British officials in India.
  3. Major supplier of cotton: India remained a major supplier of raw cotton to the British which was required to feed the cotton textile industry of Britain.
  4. Supplier of indentured workers: Many indentured workers from Bihar, UP, and central India have migrated to other countries to work in mines and plantations.

Question 5. How did the Bretton Woods System work?

Answer:

  1. The International Monetary System is the system linking national currencies and the monetary system.
  2. The Bretton Woods system was based on fixed exchange rates. In this system, the national currencies were pegged to the dollar at a fixed exchange rate.
  3. The Bretton Woods system inaugurated an era of unprecedented growth of trade and incomes for the Western industrial nations.

Question 6. Why did the European employers find it difficult to recruit labour in Africa? Write two methods they used to recruit and retain labour.

Answer:

The European employers found it difficult to recruit labour in Africa because historically, Africa had abundant land and a relatively small population.

For centuries, land and livestock sustained African livelihoods and people rarely worked for wages. Employers used the following methods to recruit and retain labour:

  1. Heavy taxes were imposed which could be paid only by working for wages on plantations and mines.
  2. Inheritance laws were changed so that peasants were displaced from the land. Only one member of a family was allowed to inherit the land, as a result of which the others were pushed into the labour market.

Question 7. Explain why the economy of the USA was strong in the early 1920s. Would you agree that the roots of the Great Depression lay in this ‘boom”? State reasons for your answer.

Answer:

The economy of the USA was strong in the early 1920s because:

  1. Mass production became a characteristic feature of industrial production in the USA. Mass production lowered the costs and prices of engineered goods.
  2. There was a spurt in the purchase of refrigerators, washing machines, radios, gramophone players through a system of hire purchase’. It was also fuelled by a boom in house construction and home ownership, financed once again by loans.

The housing and consumer boom of the 1920s created the basis of prosperity in the US. Yes; the roots of the Great Depression lay in this boom because of the overproduction in the agricultural and industrial sectors.

NCERT-Solutions-For-Class-10-History-Chapter-4-The-Making-Of-A-Global-World

Question 8. What was Corn Law? Why was the Corn Law abolished? What was the result of abolishing the Corn Law?
Or
Explain the effects of the British government’s decision to abolish the Corn Law.

Answer:

  1. The law allowing the government to restrict the import of corn was commonly known as ‘Corn Law’. This was under the pressure of landed groups.
  2. The Corn Law was abolished because industrialists and urban dwellers were unhappy with high food prices as a result of the Corn Law.
    • After the Corn Law was scrapped, food could be imported into Britain more cheaply than it could be produced within the country.
    • British agriculture was unable to compete with imports.
    • Vast areas of land were now left uncultivated, and thousands of men and women were thrown out of work. They flocked to the cities or migrated overseas.
    • As the food prices fell, consumption in Britain rose. From the mid-nineteenth century, faster industrial growth in Britain also led to higher incomes, and therefore more food imports.

Question 9. What is G-77? What were its demands?

Answer:

G-77 refers to an organised group of most of the developing countries that did not benefit from the fast growth of the Western economies experienced in the 1950s and 1960s.

Demands of G-77: It demanded a New International Economic Order (NIEO).

By the NIEO, they meant a system that would give them real control over their natural resources, more development assistance, fairer prices for raw materials, and better access to their manufactured goods in developed countries’ markets.

Question 10. Why did thousands of people flee away from Europe to America in the 19th century? State any three reasons.

Answer:

Thousands of people fled away from Europe to America in the 19th century because:

  1. After the Corn Law was scrapped, food could be imported into Britain more cheaply than it could be produced within the country. British agriculture was unable to compete with imports.
  2. Vast areas of land were now left uncultivated, and thousands of men and women were thrown out of work. They flocked to the cities or migrated overseas.
  3. Deadly diseases were widespread.
  4. Religious conflicts were common and religious dissenters were persecuted.

Question 11. Write any three factors responsible for indentured labour migration from India.

Answer:

  1. It was a world of faster economic growth as well as great misery, higher incomes for some and poverty for others, technological advances in some areas and new forms of coercion in others.
  2. Migrants were hoping to escape poverty or oppression in their home villages.
  3. Agents also tempted the prospective migrants by providing false information about final destinations, modes of travel, the nature of work, and living and working conditions.
  4. Often migrants were not even told that they were to embark on a long sea voyage. Sometimes, agents even forcibly abducted less willing migrants.

Question 12. What is meant by the Bretton Woods System? Explain.

Answer:

The main aim of the post-war international economic system was to preserve economic stability and full employment in the industrial world.

Its framework was agreed upon at the United Nations Monetary and Financial Conference held in July 1944 at Bretton Woods in New Hampshire, the USA.

The post-war international economic system is also often described as the Bretton Woods System.

It established the International Monetary Fund (IMF) to deal with external surpluses and deficits of its member nations and the World Bank for Reconstruction and Development.

The IMF and the World Bank are referred to as the Bretton Woods institutions or sometimes, the Bretton Woods twins.

Question 13. What was ‘Corn Law’? Who forced the abolition of the Corn Law?

Answer:

The law allowing the government to restrict the import of corn was commonly known as ‘Corn Law’. It was due to pressure from landed groups.

Population growth from the late eighteenth century had increased the demand for food grains in Britain.

As urban centres expanded and industry grew, the demand for agricultural products went up, pushing up food grain prices.

Unhappy with high food prices, industrialists and urban dwellers forced the abolition of the Corn Law.

Question 14. Explain three major features of the global agricultural economy that took shape towards the close of the nineteenth century.

Answer:

They are as follows:

  1. Food no longer came from a nearby village or town, but, from thousands of miles away.
  2. It was not grown by a peasant tilling his own land, but by an agricultural worker, perhaps recently arrived, who was now working on a large farm that only a generation ago had most likely been a forest.
  3. It was transported by railway, built for that very purpose, and by ships which were increasingly manned in these decades by low-paid workers from southern Europe, Asia, Africa and the Caribbean.

Question 15. What was rinderpest? State any two effects of the coming of rinderpest of Africa.

Answer:

Rinderpest was a devastating, fast-spreading disease caused by cattle plague. It arrived in Africa in the late 1880s. It was carried by the infected cattle imported from British Asia to feed the Italian soldiers invading Eritrea in East Africa.

Effects:

  1. Rinderpest entered Africa from the east, and moved to the west like ‘forest fire’.
  2. It killed about 90% of the cattle. The loss of cattle destroyed African livelihoods.
  3. Planters, mine owners and colonial governments now successfully monopolised what scarce cattle resources remained, to strengthen their power and to force Africans into the labour market.
  4. Control over the scarce resource of cattle enabled the European colonisers to conquer and subdue Africa.

Question 16. What was the impact of the Great Depression of 1929 on the Indian economy?
Or
Write any three impacts of the Great Depression of 1929 on the Indian Economy.

Answer:

Impact of the Great Depression on Indian economy:

  1. As international prices crashed, prices in India also plunged. Between 1928 and 1934, wheat prices in India fell by 50 per cent. Peasants and farmers suffered more than urban dwellers.
  2. The colonial government refused to reduce revenue demands. Jute producers were hit badly as jute prices fell when gunny exports collapsed.
  3. Across India, peasants’ indebtedness increased. They used up their savings, mortgaged lands, and sold whatever jewellery and precious metals they had to meet their expenses.
  4. The depression proved less grim for urban India. Because of falling prices, those with fixed incomes – say town-dwelling landowners who received rents and middle-class salaried employees – now found themselves better off. This was because everything cost less.
  5. Industrial investment also grew as the government extended tariff protection to industries, under the pressure of nationalist opinion.

Question 17. Explain the impact of the First World War on Britain’s economy.
Or
Assess the impact of the First World War on Britain’s economy.

Answer:

  1. After the War, Britain found it difficult to recapture its earlier position of dominance in the Indian market and to compete with Japan internationally.
  2. Moreover, to finance war expenditures, Britain had borrowed liberally from the US. This meant that, at the end of the War, Britain was burdened with huge external debts.
  3. The War had led to an economic boom, i.e., a huge increase in demand, production and employment. When the war boom ended, production contracted and unemployment increased.
  4. At the same time, the government reduced bloated war expenditures to bring them into line with peacetime revenues. These developments led to huge job losses.

Question 18. What was the impact of the First World War on the socio-economic conditions of the world? Write any three points.

Answer:

  1. Entire societies were reorganised for war – as men went to battle, women stepped into undertake jobs that earlier only men were expected to do.
  2. The war led to the snapping of economic links between some of the world’s largest economic powers which were now fighting each other to pay for them.
  3. So, Britain borrowed large sums of money from the US banks as well as the US public. Thus, the war transformed the US from being an international debtor to an international creditor.
  4. Many agricultural economies were also in crisis. Before the war, Eastern Europe was a major supplier of wheat in the world market. The supply was disrupted during the War.

After the War, production revived and created a glut in wheat output. Grain prices fell, rural incomes declined, and farmers fell deeper into debt.

Question 19. Explain what we mean when we say that the world ‘shrank’ in the 1500s.
Or
“The pre-modern world shrank greatly in the 16th century.” Justify the statement.

Answer:

The pre-modern world shrank greatly in the 16th century because:

  1. Europe’s soldiers discovered new sea routes to Asia and America.
  2. The Indian subcontinent was the centre of bustling trade in Asia since ancient times. The discovery of new sea routes helped the Europeans to drive the trade towards Europe.
  3. Besides mercantilist expansion, the spread of Christianity was another factor which guided the Europeans to travel to faraway regions.

Question 20. Briefly summarise the two lessons learnt by the economists and the politicians from the inter-war economic experience.

Answer:

Economists and politicians drew the following lessons from the inter-war economic experiences:

  1. An industrial society based upon mass production cannot sustain itself without mass consumption. To ensure mass consumption, incomes have to be stable and high, and employment has to be adequate.
    • The markets can never fulfil the condition of full employment.
    • Therefore, governments should interfere to minimise shifts in output, prices and employment levels. Economic stability can be only ensured through government efforts.
  2. The second lesson was linked to a country’s economic relations with other countries. The aim of full employment could only be achieved if the government had the authority to regulate the flow of goods, capital and labour.

Question 21. Who profits from jute cultivation according to the jute growers’ lament? Explain.

Answer:

The traders gained extensive profits from trading in jute. On the other hand, the growers and cultivators of jute led miserable lives, as the prices paid to them for their produce were very low.

Jute was cultivated in Bengal on a large scale. Its increasing demand in the world market forced the cultivators to produce more jute. They borrowed money and took loans to cultivate jute.

At the time of the Great Depression, the prices of jute products fell considerably. As a result, the cultivators faced many losses and suffered immensely.

Question 22. Discuss the importance of language and popular traditions in the creation of national identity.

Answer:

A person is identified as belonging to a particular nation by his cultural traditions. and the language that he speaks.

The languages as well as the traditional practices usually develop and get established over a long period of time. They give an identity to an individual wherever he is.

Thus, a French national will always speak the French language or follow French customs wherever he goes in the world.

Chapter 4 The Making Of A Global World Multiple Choice Questions And Answers

Question 1. What is Rinderpest?

  1. A person
  2. A cattle disease
  3. A place
  4. A monument

Answer: 2. A cattle disease

Question 2. Who made the best cutting decision?

  1. Henry Ford
  2. James Watt
  3. James Ford
  4. Henry Herold

Answer: 1. Henry Ford

Question 3. Which among the following were considered as Allies Power?

  1. Britain, France, Russia
  2. Germany, Austria-Hungary and Ottoman Turk
  3. Japan, France and Germany
  4. Britain, Japan and Russia

Answer: 1. Britain, France, Russia

Question 4. Which one of the following institutions was established in the Bretton Woods Conference?

  1. International Security Fund
  2. International Monetary Fund
  3. Indian Monetary Fund
  4. International Labour Organisation

Answer: 2. International Monetary Fund

Question 5. Who adopted the concept of an assembly line to produce automobiles?

  1. T. Coppola
  2. V. S. Naipaul
  3. Henry Ford
  4. Ramesh Sarwan

Answer: 3. Henry Ford

Question 6. Which among the following countries were considered Axis Powers during the Second World War?

  1. Nazi Germany, Japan, Italy
  2. Britain, Germany, Russia
  3. France, Germany, Italy
  4. Britain, France, Russia and the US

Answer: 1. Nazi Germany, Japan, Italy

Question 7. Which one of the following did not travel along the silk routes in the pre-modern world?

  1. Christian missionaries
  2. Traders
  3. Tourists
  4. Muslim preachers

Answer: 3. Tourists

Question 8. Which one of the following is a Nobel Prize-winning writer who is a descendant of indentured labour from India?

  1. Salman Rushdie
  2. V. S. Naipaul
  3. Arundhati Roy
  4. Bob Marley

Answer: 2. V. S. Naipaul

Question 9. Which of the following West Indies cricketers trace their roots to indentured labour migrants from India?

  1. Vivian Richards and Gary Sobers
  2. Chris Gayle and Dwayne Bravo
  3. Ramnaresh Sarwan and Shivnarine Chanderpaul
  4. Brian Lara and Courtney Walsh

Answer: 3. Ramnaresh Sarwan and Shivnarine Chanderpaul

Question 10. What is El Dorado in South America?

  1. It was the place where Columbus landed
  2. Where silver mines were located
  3. A fabled city of gold
  4. A famous slave market

Answer: 3. A fabled city of gold

Question 11. ‘Silk Route’ refers to:

  1. Network of routes connecting China and Rome
  2. Network of routes connecting India and Rome
  3. Network of routes connecting China and India
  4. Network of routes connecting Asia with Europe and Northern Africa

Answer: 4. Network of routes connecting Asia with Europe and Northern Africa

Question 12. What was the Bretton Woods system?

  1. Post-war military system
  2. Post-war political system
  3. Post-war international economic system
  4. None of these

Answer: 3. Post-war international economic system

Question 13. Which of the following groups demanded the Right to Vote for Adult Males in Britain during the 18th century?

  1. The Christian Movement
  2. Temperance Movement
  3. The Dock Workers’ Movements
  4. Chartism Movement

Answer: 3. The Dock Workers’ Movements

Question 14. Which of the following is the first European country that conquered America?

  1. France
  2. Britain
  3. Spain
  4. Germany

Answer: 3. Spain

Question 15. What do you mean by G-77?

  1. Group of rich countries
  2. Group of African countries
  3. Group of Asian countries
  4. Group of developing countries

Answer: 4. Group of developing countries

Question 1. Picture Based Question

Look at the given picture and answer the questions that follow:

NCERT Solutions For Class 10 Social Science History Chapter 4 The Making Of A Global World New yark Herlad On The Mission

(1) Who was Stanley? By whom and on what mission was he sent?

Answer:

Stanley was a known journalist and explorer. He was sent by the New York Herald on a mission to find Livingston. Livingston was a missionary and explorer who had been in Africa for several years.

(2) How did Stanley reach there?

Answer:

Like other European and American explorers of the time, Stanley went with arms.

(3) Who helped him there to fight with local tribes?

Answer:

He was helped by mobilised local hunters, warriors and labourers to fight with local tribes.

Question 2. Source Based Question

Read the extract taken from your NCERT Textbook, then answer the following questions:

In spite of my best efforts, I could not properly do the work that was allotted to me. In a few days, I got my hands bruised all over and I could not go to work for a week for which I was prosecuted and sent to jail for 14 days.

New emigrants find the tasks allotted to them extremely heavy and cannot complete them in a day… Deductions are also made from wages if the work is considered to have been done unsatisfactorily.

Many people cannot therefore earn their full wages and are punished in various ways. In fact, the labourers have to spend their period of indenture in great trouble.

(1) Name the source of this passage.

Answer:

The passage has been taken from the testimony of Ram Narain Tiwari. He was an indentured labourer. It has been taken from the Department of Commerce and Industry, Emigrant Branch, 1916.

(2) Why could the writer not properly do the work allotted to him?

Answer:

The writer could not do the allotted work properly because he got his hand bruised all over.

(3) What punishment was given to the writer for not going to work?

Answer:

He was prosecuted and sent to jail for 14 days.

NCERT Solutions For Class 10 History Chapter 8 Novels Society And History

Chapter 8 Novels Society And History Important Dateline

  • 1719: Daniel Defoe’s novel ‘Robinson Crusoe’ was published.
  • 1740: Circulating libraries were introduced.
  • 1854: ‘Hard Times’ published.1857: Baba Padamji’s ‘Yamuna Paryatan’ was published.
  • 1878: ‘Rajasekhara Caritamu’ published by Kandukuri virselingam
  • 1889: The novel ‘Indulekha’ was published by O. Chandu Menon.
  • 1894: Rudyard Kipling published Jungle Book.
  • 1905: ‘Sultana’s Dream’ written by Rokeya Hossein.
  • 1936: Prem Chand’s ‘Godan’ was published.
  • 1956: Advaita Malla Barman’s “Titash Ekti’ Nadir Naam was published.

NCERT Solutions For Class 10 Social Science History Chapter 8 Novels Society And History

Chapter 8 Novels Society And History Important Concepts And Terms

Novel: A novel is an extended, generally fictional narrative, typically in prose.

Gentlemanly Classes: People who claimed noble birth and high social position. They were supposed to set the standard for proper behavior.

Epistolary: Written in the form of a series of letters.

Serialized: A format in which the story is published in installments, each part in a new issue of the journal.

Vernacular: The normal, spoken form of a language rather than the formal, literary form.

Satire: A form of representation through writing, drawing, painting, etc., that provides a criticism of society in a manner that is witty and clever.

Chapter 8 Novels Society And History Ncert Textbook Exercises

Question 1. Explain the following:

  1. Social changes in Britain led to an increase in women readers.
  2. What actions of Robinson Crusoe make us see him as a typical colonizer?
  3. After 1740, the readership of novels began to include poorer people.
  4. Novelists in colonial India wrote for a political cause.

Answer:

  • As the middle classes became more affluent, women got more leisure to read and write novels. Also, novels began to explore the world of women, their emotions, identities, experiences, and problems.
    • Domestic life became an essential subject of novels – a field women had the authority to speak about.
  • Robinson Crusoe’s actions that make us see him as a typical colonizer are many. Shipwrecked on an island inhabited by colored people, Crusoe treats them as inferior beings.
    • He is portrayed as “rescuing” a native and then making him a slave. He gives him the name Friday, without even caring to ask for his name.
    • Colonized people were seen as barbaric and primitive, and colonialism became their self-professed civilizer. Crusoe was a direct representation of this ideology of colonizers.
  • After 1740, the readership of novels began to include poorer people because of the introduction of circulating libraries, low-priced books, and also because of the system of hiring out of books by the hour.
    • This made books easily available to poor people, who could not afford books earlier due to high costs and the absence of lending libraries.
  • Novelists in colonial India wrote for a political cause because the novel was a powerful medium for expressing social defects and suggesting remedies for the same.
    • It also helped establish a relationship with the past. Since people from all walks of life could read novels, it was an easy way to popularise anti-colonial ideas.
    • It also helped bring about a sense of national unity among the people.

Question 2. Outline the changes in technology and society which led to an increase in readers of the novel in eighteenth-century Europe.

Answer:

  1. Print-made novels to be read widely and become popular quickly.
  2. Novels produced a number of common interests and a variety of readers.
  3. Readers were drawn into the story and identified themselves with the lives of fictitious characters. They now could think about issues like love and marriage, and proper conduct for men and women.
  4. Prosperity, due to industrialization, made new groups join the readership for novels. Besides the aristocratic and gentlemanly classes, new groups of lower-middle-class people such as shopkeepers and clerks joined in.
  5. The rise in the earnings of authors freed them from the patronage of aristocrats. They could now experiment with different literary styles. The epistolary novel – Samuel Richardson’s Pamela – written in the 18th century was the first of its kind. It was a story told through letters.
  6. Books became cheap and even the poor could buy them. Circulating libraries made books easily accessible. Publishers also started hiring out novels. Books could now be read in private or could be heard by more people, while one of them read it out.
  7. Magazines serialized stories (Charles Dickens’s Pickwick Papers was the first), illustrated them, and sold them cheaply. All these changes increased the number of readers.

Question 3. Write a note on:

  1. The Oriya novel
  2. Jane Austen’s portrayal of women
  3. The picture of the new middle class which the novel Pariksha-Guru portrays.

Answer:

  1. In 1877-78, Ramashankar Ray started to serialize the first Oriya novel, “Saudamini”; but it remained incomplete. Orissa’s first major novelist was Fakir Mohon Senapati.
    • He wrote “Chaa Mana Atha Guntha” which deals with land and its possession. This novel illustrated that rural issues could be an important part of urban concerns.
  2. The novels of Jane Austen give us a glimpse of the world of women in genteel rural society in mid-19th century Britain.
    • Women, at that time, were encouraged to look for a good marriage and find a wealthy and proper husband. Her famous novel ‘Pride and Prejudice’ depicts this well.
    • It writes, ‘It is the truth, universally acknowledged, that a single man in possession of a good fortune must be in want of a good wife’. The main characters are shown to be preoccupied with marriage and money.
  3. The novel “Pariksha-Guru” portrays the difficulties of the new middle class in adapting to colonized society while preserving its cultural identity.
    • It emphasizes that Western ideals must be inculcated, but without sacrificing the traditional values of middle-class households.
    • The characters in this Hindi novel by Srinivas Das are seen endeavoring to bridge the two different worlds of modern education and traditional ethics.

Question 4. Discuss some of the social changes in nineteenth-century Britain that Thomas Hardy and Charles Dickens wrote about.

Answer:

Social changes in nineteenth-century Britain highlighted by Thomas Hardy are:

  1. The breaking up of rural communities because of industrialization. Due to industrialization, peasants who toiled with their lands were disappearing as large or big farmers enclosed lands, bought machines, and employed laborers to produce for the market.
  2. In his novel ‘Mayor of Casterbridge’, Hardy mourns the loss of the more personalized world which is being replaced by a more efficiently managed urban culture.

Social Changes Highlighted by Charles Dickens are:

  1. Charles Dickens wrote mainly about the emergence of the industrial its effects on society and the common people.
  2. The growth of factories and expanded cities led to the growth of business and economy and increased the profits of capitalists.
  3. At the same time, workers faced immense problems. The use of machines resulted in the unemployment of ordinary laborers; they became homeless, creating a problem with housing.
    • The pursuit of profit became the goal of factory owners while the workers were undervalued and almost lost their identity. Human beings were reduced to being mere instruments of production.

Question 5. Summarise the concern in both nineteenth-century Europe and India about women reading novels. What does this suggest about how women were viewed?

Answer:

The concern in both nineteenth-century Europe and India about women reading novels bore more or less similar fears.

Women were seen as easily corruptible and an imaginary world that the novel provided was seen as a dangerous opening for the imaginations of its readers.

In certain Indian communities, it was felt that women who read novels would leave their domestic environments and aspire to be part of the outside world – the male domain.

This suggests that women were viewed as delicate and incapable of being independent.

They were merely expected to marry a man who could take care of their financial needs while they maintained his household and remained subservient to him.

Question 6. In what ways was the novel in colonial India useful for both the colonizers as well as the nationalists?

Answer:

The novel in colonial India was useful for both the colonizers as well as the (CBSE 2009) nationalists on account of a variety of reasons.

Colonial rulers found “vernacular” novels illuminating the information they provided on native customs and life. The novel was useful in the governance of this diverse country.

Indian nationalists used the form of the novel to criticize colonial rule and instill a sense of national pride and unity among the people.

Question 7. Describe how the issue of caste was included in the novels in India. By referring to any two novels, discuss the ways in which they tried to make readers think about existing social issues.

Answer:

Indians used novels as a powerful medium to criticize what they considered defects in their society and to suggest remedies.

The issue of caste was included in the Indian novels for this same purpose. Novels like Indirabai and Indulekha were written by members of the upper castes with upper-caste characters.

  • Potheri Kunjambu, a lower-caste writer from north Kerala, wrote a novel called Saraswativijayam in 1892. It was a direct attack on caste oppression.
    • The novel’s hero, an ‘untouchable’ leaves his village to escape from the cruelty of a Brahmin overlord.
    • He converts to Christianity, receives modern education, and returns to his village as a judge of a local court.
    • In the meantime, the villagers bring the landlord to his court, they believe the landlord’s men have killed the hero.
    • The judge reveals himself and the Nambuthri landlord repents and promises to reform. The novel emphasizes the role of education in uplifting the lower classes.
  • In 1920, a Bengali novel Titash Ekti Nadir Naam written by Advaita Malla Burman took up the cause of low castes.
    • The people described are the Mallas – a community of fishermen. The story covers three generations and describes the oppression of the upper castes.
    • The lives of the Mallas are tied to the river Titash. As the river dries, the community dies too.
    • This novel is special because the author himself was a ‘low caste’ describing the anguish of low-caste people.

Question 8. Describe the ways in which the novels in India attempted to create a sense of pan-Indian belonging.

Answer:

The ways in which the novels in India attempted to create a sense of pan-Indian belonging were:

  1. Many historical novels were about Marathas and the Rajputs which produced a sense of a pan-Indian belonging in Bengal.
  2. They imagined the nation to be full of adventure, heroism, romance, and sacrifice. The novels allowed the colonized to give shape to their desires.
  3. Bankim’s Anandmath is a novel about a secret Hindu militia that fought Muslims to establish a Hindu kingdom. It was a novel that inspired many freedom fighters.
  4. Shivaji, the hero of the novel Anguriya Binimoy (1857) written by Bhudeb Mukhopadhyaya (1825-94) engages in many battles against clever and treacherous Aurangzeb. What gave him courage and grit was his belief that he was a nationalist fighting for the freedom of Hindus.
  5. Imagining a heroic past was one way in which the novel helped popularise the sense of belonging to a common nation. It was another way to include various classes in the novel so that they could be seen as belonging to a shared world. Premchand’s novels, for instance, are filled with all kinds of powerful characters drawn from all levels of society.

Chapter 8 Novels, Society And History Short Questions And Answers

Question 1. Novels were useful for both colonial administrators and Indians in colonial India.
Support the statement with an example.

Answer:

To colonial administration:

  1. A source to understand native life and customs.
  2. Novels helped to govern Indian society with various communities and castes.
  3. Those helped me to learn the domestic life, dresses, religious worship, etc.
  4. Some of the books were translated into English by British administrators or Christian missionaries.

Read and Learn More Class 10 Social Science Solutions

To Indians:

  1. Indians used the novels as a powerful medium to criticize defects that they considered in society and to suggest remedies.
  2. To establish a relationship with its past.
  3. To propagate their ideas about society.
  4. Novels glorified the accounts of the past and helped create a sense of National Pride among the readers.
  5. Those helped in creating a sense of collective belongingness on the basis of one’s language.

Question 2. Explain how novels became a popular medium of entertainment among the middle class during the late 19th century.

Answer:

  1. The world created by novels was absorbing, believable, and seemingly real.
  2. While reading novels, the readers are transported to another person’s world and begin looking at life as it was experienced by the characters of the novel.
  3. Novels allowed individuals the pleasure of reading in private as well as in public.
  4. The stories of novels were discussed in homes, meetings, or even in offices.

Question 3. What were the advantages of serialized novels?

Answer:

  1. A story is published in installments, keeping the suspense for the next issue.
  2. Serialization allowed readers to relish the suspense, discuss the characters of a novel, and live for weeks with their stories.
  3. This was possible since the magazines were illustrated, cheap, and affordable.

Question 4. What were the advantages of vernacular novels?

Answer:

  1. They were written in the language of common people.
  2. Vernacular novels produced a sense of a shared world between diverse people of a nation.
  3. Novels also draw from different styles of languages. A novel may be written in a classical language combined with the language of the street to make them all a part of the vernacular that it uses,
  4. Novels were read individually. Sometimes in groups also.

NCERT-Solutions-For-Class-10-History-Chapter-8-Novels-Society-And-History

Question 5. Describe any two popular themes on which women writers in England wrote in the 19th century.

Answer:

Domestic Life: Women writers wrote about domestic life themes with which they (CBSE 2010) were familiar. For this, they drew upon their experience and earned public recognition.

For instance, the novels of Jane Austen depict a society that encouraged women to look for ‘good’ marriages and find wealthy husbands.

Rebellious Women: Women novelists, like Charlotte Bronte, dealt with women who rebelled against existing norms of society before adjusting to them.

In her novel Jane Eyre, Jane is shown as independent and assertive. While girls of her age were supposed to be docile, meek, and well-behaved, Jane was shown protesting against the hypocrisy of her elders.

Question 6. Explain, how novels became a popular medium of entertainment among the middle class during the late 19th century in India.

Answer:

The circulation of printed books allowed people to assure themselves in new ways. (CBSE, Delhi 2010) Picture books, translations from other languages, popular songs sometimes composed in contemporary events, stories in newspapers and magazines–all these offered new forms of entertainment. Within this new culture of print, novels soon became immensely popular.

In Tamil, for example, there was a flood of popular novels in the early decades of the 20th century. Detective and mystery novels often had to be printed again and again to meet the demands of the readers.

In the late 19th century and the early 20th century, written texts were often read aloud for several people to hear.

Individuals sitting at home or traveling in trains enjoyed them.

Question 7. Write three methods by which printed books became more accessible to people.

Answer:

There were a series of innovations in the printing technology in the 19th century.

  1. Richard M. Hoe of New York perfected the power-driven cylindrical press. He could print 8,000 sheets per hour. His press was very useful for printing newspapers.
  2. The late 19th century saw the development of the offset press capable of printing six colours at a time.
  3. Electrically-operated press in the early 20th century increased the rate of printing operations.
  4. Methods of feeding paper improved, the quality of plates became better, machines were fed, and automatic paper reels and photoelectric controls of the color register were introduced.

Question 8. How did the novels contribute to the growth of nationalism in Europe?

Answer:

Within the novel, people can see people living in different worlds and sharing a collective identity.

By identifying with their collective identity people felt they belonged to one nation even though they were living in different places.

Question 9. What was the theme of the novel written by Thomas Hardy?

Answer:

The theme of novels written by Thomas Hardy was about the farming communities of England that were breaking up due to the mechanization of agriculture.

Question 10. What were the themes of novels for the young during the 19th century in England?

Answer:

The popular themes were historical adventures of young boys who got involved in some military action and showed courage.

Question 11. What is the importance of Sewasadan by Prem Chand in the History of novels in India?

Answer:

Sewasadan deals with the poor condition of women in the society. It forces the readers to get out of world fantasies and seriously ponder over real-life issues that are confronted by ordinary people.

Question 12. Why did Colonial rulers find Indian novels useful?

Answer:

Indian novels gave colonizers an insight into the lives of the colonized people, their traditions, and their culture.

The Britishers being outsiders knew nothing about the varied customs prevalent in various Indian societies.
This helped them in framing their administrative policies.

Question 13. Novels are useful for the nationalists. Explain. Answer:

The nationalists got an opportunity to glorify the accounts of the past. These novels helped in creating the feeling of Nationalism.

Novels inspired political movements – Anandamath inspired many freedom fighters.

Question 14. Describe the pleasure of reading novels.

Answer:

It offers a popular medium of entertainment. The novels spread the way of silent reading because novels are generally read alone and in silence.

Question 15. Describe the reason for the popularity of novels among women.

Answer:

The reason for the popularity of novels among women was that it allowed for a new conception of womanhood. Stories of love showed women who could choose or refuse their partners and relationships.

Question 16. Write a brief description of Rokeya Hossein and her novels.

Answer:

Rokeya Hossein (1880-1932) was a reformer, who wrote a satiric fantasy in English called ‘Sultana’s Dream’ (1905) which shows a topsy-turvy world in which women take the place of men.

Her novel Padmarag also showed the need for women to reform their condition through their own actions.

Question 17. What was the effect of men’s suspicion about women writing novels or reading them?

Answer:

As men became suspicious of women writing novels or reading them, they started writing in secrecy. Sailabala Ghosh Jaya, a popular novelist, could only write because her husband protected her.

Question 18. What was the attitude of people in India in the 19th century towards women reading? How did women respond to this?

Answer:

There was not a universally favorable attitude.

Conservative Hindus believed that a literate girl would be widowed and Muslims feared educated women would be corrupted by reading Urdu romances. Rebel women defied such prohibition.

A Muslim girl in north India defied her family and secretly learned to read and write Urdu. Rashsundari Debi, a young married girl in a very orthodox family, learned to read in the secrecy of her kitchen. Later she published her autobiography in Bengali.

A few Bengali women like Kailash Bashini Debi wrote books highlighting the experiences of women. In the 1860s, Tarabai Shinde and Pandita Ramabai of Maharashtra wrote about the miserable lives of upper-caste women.

Women writing in Tamil expressed their gratitude to books. The attitude in general was to keep women imprisoned at home, ignorant, forced to do hard domestic work, and subject to unfair treatment.

In Punjab, folk literature exhorted women to be obedient wives (Ram Chaddha’s Istri Dharm Vichar).

The Khalsa Tract Society published cheap booklets with the same message. In Bengal, – an entire area in Central Calcutta- the Battala – was devoted to printing popular books. They were cheap editions of religious texts, scriptures as well as scandalous literature.

Women’s education was not encouraged by the majority as Begum Rokeya Sakhawat Hossein reported in her address to Bengal Women’s Educated Conference.

Question 19. Which form did the epistolary novel use to tell its story? Explain with an example.

Answer:

The epistolary novel uses the private and personal form of letters to tell its story.

For example, Samuel Richardson’s Pamela, written in the eighteenth century, told much of its story through an exchange of letters between two lovers. These letters tell the reader of the. Eden conflicts in the heroine’s mind.

Question 20. Briefly describe the two earliest novels in Marathi.

Answer:

Yamuna Paryatan and Muktamala were the two earliest novels in Marathi.

  1. Yamuna Paryatan (1857). This was the first novel in Marathi. Its author was Baba Padmanji. It used a simple style of storytelling to speak about the plight of widows.
  2. Muktamala (1861). Lakshman Moreshwar Halbe’s Muktamala was the second Marathi novel. This was not a realistic novel; it presented an imaginary ‘romance’ narrative with a moral purpose.

Question 21. In which two worlds did the early Bengali novels live in the 19th century?

Answer:

In the 19th century, the early Bengali novels lived in the following two worlds:

  1. Many of the novels were located in the past, their characters, events and love stories based on historical events.
  2. Another group of novels depicted the inner world of domestic life in contemporary settings. Domestic novels frequently deal with the social problems and romantic relationships between men and women.

Question 22. What do you know about the languages of the novel?

Answer:

The novel uses the vernacular, the language that is spoken by common people. By coming close to the different spoken languages of the people, the novel produces the sense of a shared world between diverse people in a nation.

The novel also draws from different styles of language. A novel may take a classical language and combine it with the language of the streets and make them all a part of the vernacular that it uses. Like the nation, the novel brings together many cultures.

Question 23. What do you know about the development of the novel in Assam?

Answer:

  1. The first novels in Assam were written by the missionaries. Two of them were translations of Bengali including Phulmoni and Karuna.
  2. In 1888, Assamese students in Kolkata formed the Asamya Bhasar Unnatisadhan which brought out a journal called Jonaki. This journal opened up opportunities for authors to develop the novel.
  3. Rajanikanta Bardoloi wrote the first major historical novel in Assam called Manomati (1900).
    • It is set in the Burmese invasion, stories of which the author had probably heard from old soldiers who had fought in the 1819 campaign.
    • It is a tale of two lovers belonging to two hostile families who are separated by the war and finally reunited.

Question 24. What message does Gulavadi Venkata Rao’s novel convey?

Answer:

In Gulavadi Venkata Rao’s novel Indirabai, the heroine is given away in marriage at a very young age to an elderly man. Her husband dies soon after, and she is forced to lead the life of a widow.

Despite opposition from her family and society, Indirabai succeeds in continuing her education. Eventually, she marries again, this time a progressive, English-educated man.

Women’s education, the plight of widows, and problems created by the early marriage of girls were important issues for social reformers in Karnataka at that time.

Chapter 8 Novels Society And History Multiple Choice Question And Answers

Question 1. Oliver Twist was written by

  1. Emile Zola
  2. Thomas Hardy
  3. Jane Austen
  4. Charles Dickens

Answer: 4. Charles Dickens

Question 2. Jane Austen’s famous novel was

  1. Hard Times
  2. Pride and Prejudice
  3. Jane Eyre
  4. Jungle Book

Answer: 2. Pride and Prejudice

Question 3. Which of the following novels was not written by Charles Dickens?

  1. Hard Times
  2. Germinal
  3. Oliver Twist
  4. Pickwick Papers

Answer: 2. Germinal

Question 4. Who wrote the ‘Jungle Book’?

  1. Charlotte Bronte
  2. R. L. Stevenson
  3. Rudyard Kipling
  4. None of these

Answer: 3. Rudyard Kipling

Question 5. The earliest Indian novel was written in which of the following languages?

  1. Tamil
  2. Hindi
  3. Bengali
  4. Telugu

Answer: 3. Bengali

Question 6. The first modern novel in Malayalam is

  1. Swarna Lekha
  2. Indu Lekha
  3. Sindu Lekha
  4. None of these

Answer: 2. Indu Lekha

Question 7. Who is the pioneer of modern Hindi literature?

  1. Bharatendu Harishchandra
  2. Srinivas Das
  3. Devaki Nandan Khatri
  4. Munshi Premchand

Answer: 1. Bharatendu Harishchandra

Question 8. The first modern Hindi novel is:

  1. Parikhsha-Guru
  2. Godan
  3. Chandrakanta
  4. Sevasadan

Answer: 1. Parikhsha-Guru

Question 9. Which was the first novel written by Bankim Chandra Chatterjee?

  1. Anandmath
  2. Sultana’s Dream
  3. Muktamala
  4. Durgeshnandini

Answer: 4. Durgeshnandini

Question 10. Which one of the following novels is written by Rokeya Hussein?

  1. Pariksha Guru
  2. Godan
  3. Anandmath
  4. Sultana’s Dream

Answer: 4. Sultana’s Dream

Question 11. Which of the following novels deals with caste oppression?

  1. Sultana’s Dream
  2. Indu Lekha
  3. Saraswativijayam
  4. Godan

Answer: 3. Saraswativijayam

Question 12. Which was the first historical novel written in Bengali?

  1. Anandamath
  2. Anguriya Binimoy
  3. Sultana’s Dream
  4. Durgesh Nandini

Answer: 2. Anguriya Binimoy

Question 13. Who was the central character of Prem Chand’s Rangbhoomi?

  1. Tulsidas
  2. Surdas
  3. Kabirdas
  4. None of these

Answer: 2. Surdas

Question 14. Which of the following novels was not written by Munshi Premchand?

  1. Rangbhoomi
  2. Godan
  3. Sewasadan
  4. Pariksha-Guru

Answer: 4. Pariksha-Guru

Question 15. Name the novel which was based on the effect of industrialization.

  1. Hard Times
  2. Oliver Twist
  3. Germinal
  4. Pickwick Papers

Answer: 1. Hard Times

Question 16. What is an ‘epistolary novel’?

  1. A novel written in a series of letters.
  2. A novel based on a biographical account
  3. A novel written in poetic verse
  4. None of these.

Answer: 1. A novel written in a series of letters.

1. Passage Based Questions And Answers

1. Identify famous characters from novels (mentioned in your textbook), after reading the following clues. Write the name of the character, the name of the novel, and the name of the authorities.

  1. He is a blind ‘untouchable’ beggar who struggled against the forcible takeover of his land and set up a tobacco factory.
  2. She was an intelligent and educated upper-caste woman who challenged the existing practices and married an educated man outside her caste.
  3. He was shipwrecked on an Island, rescued a native, and named him ‘Friday’, without conduction even bothering to ask him a name.
  4. She was an independent and assertive young girl who challenged the hypocrisy of elders.

Answer:

  1. The name of the character is Surdas.
    • The name of the Novel is Rangbhoomi.
    • The author of the novel-Prem Chand.
  2. The name of the character is Indulekha.
    • The name of the novel is also Indulekha.
    • The name of the author is Menon. (the main character of Madhuban).
  3. The name of the character is Robinson Crusoe.
    • The name of the novel is Mayor of Casterbridge (1886). The author’s name is Daniel Defoe.
  4. The name of the character’. The name of the novel is Jane Eyre. The Author’s name is Charlotte Bronte’s.

2. Matching of Columns

Match the books given in Column A with the name of the author

NCERT Solutions For Class 10 Social Science History Chapter 8 Novels Society And History Match The Column

Answer: 1.-(c) 2.-(d) 3.-(e) 4.-(a) 5.-(b).

3. Puzzle Solving Questions And Answers

Solve the crossword puzzle with the help of the given below clues.

Across:

2. A book written in the form of a series of letters.

5. Traditional art of storytelling.

6. A format in which the story is published in installments, each part in a new issue.

8. Language spoken by common people.

Down:

1. Writer of a novel.

3. A form of writing that criticizes society in a witty and clever way.

4. Indulekha married a groom belonging to this caste in Kerala.

7. Prose tales of adventure and heroism.

NCERT Solutions For Class 10 Social Science History Chapter 8 Novels Society And History Crossword Puzzle

Answer:

  1. JANE EYRE
  2. EPISTOLARY
  3. SATIRE
  4. NAYAR
  5. KISSA-GOI
  6. SERIALISED
  7. DASTAN
  8. VERNACULAR

NCERT Solutions For Class 10 Social Science History Chapter 8 Novels Society And History Crossword Puzzle.

NCERT Solutions For Class 10 History Chapter 7 Print Culture And The Modern World

Chapter 7 Print Culture And The Modern World Important Dateline

  • 768-770 CE: Hand Print technology comes to Japan.
  • 868 CE: The first Japanese book ‘Diamond Sutra’ was published.
  • 1430s: Gutenberg developed the first well-known printing press.
  • 1753: Kitagawa Utamaro born in Edo.
  • 1508: Erasmus wrote Adages.
  • 1517: Martin Luther wrote 95 theses.
  • 1812: The Grimm Brothers in Germany compiled folk tales.
  • Mid-16th century: Print comes to India. The first Printing Press was set up in Kolkata.
  • 1822: Persian Newspaper Jam-i-Jahan Nama and Shamsul Akhbar published.
  • 1867: Deoband Seminary was founded.
  • 1870s: Caricature and cartoons began to publish
  • 1871: Gulamgiri a famous novel published.
  • 1878: The Vernacular Press Act was passed.
  • 1920s: Chap Books series published in England.

NCERT Solutions For Class 10 Social Science History Chapter 7 Print Culture and The Modern World

Chapter 7 Print Culture And The Modern World Important Concepts And Terms

Calligraphy: The art of beautiful and stylized writing.

Vellum: A parchment made from the skin of animals.

Platen: In letterpress printing, platen is a board that is pressed onto the back of the paper to get the impression from the type. At one time it used to be a wooden board; later it was made of steel.

Compositor: The person who composes the text for printing.

Gallery: Metal frame in which types are laid and the text composed.

Ulema: Legal scholar of Islam and the Sharia (a body of Islamic Law).

Ballad: A historical account or folk tale in verse, usually sung or recited.

Fatwa: A legal pronouncement on Islamic law usually given by a mufti (legal scholar) to clarify issues on which the law is uncertain.

Taverns: Places where people gather to drink alcohol, serve food, meet friends, and exchange news.

Protestant Reformation: A sixteenth-century movement to reform the Catholic Church dominated by Rome. Martin Luther was one of the main protestant reformers. Several traditions of anti-catholic Christianity developed out of the movement.

Seditious: Action, speech, or writing that is seen as opposing the government.

Inquisition: A former Roman Catholic court for identifying and punishing heretics.

Heretical: Beliefs that do not follow the accepted teachings of the Church. In Medieval times, heresy was seen as a threat to the right of the church to decide on what should be believed and what should not. Heretical beliefs were severely punished.

Satiety: The state of being fulfilled much beyond the point of satisfaction. Dominations: Subgroups within a religion.

Almanac: An annual publication giving astronomical data, information about movements of the sun and moon, timing of full tides and eclipses, and much else that was of importance in the everyday life of people.

Chapbook: A term used to describe pocket-size books that are sold by traveling pedlars called Chapman. These became popular from the time of the sixteenth-century print and revolution.

Despotism: A system of government in which absolute power is exercised in an individual, unregulated by legal and constitutional checks.

Novel: A novel is a modern form of literature. It is born from print, a mechanical invention.

Chapter 7 Print Culture And The Modern World Ncert Textbook Exercises

Question 1. Give reasons for the following:

  1. Woodblock print only came to Europe after 1295.
  2. Martin Luther was in favor of print and spoke out in praise of it.
  3. The Roman Catholic Church began keeping an Index of Prohibited books in the mid-sixteenth century.
  4. Gandhi said the fight for Swaraj is a fight for liberty of speech, liberty of the press, and freedom of association.

Answer:

  1. Woodblock print was invented around the sixth century in China. It came to Europe, along with Marco Polo, in 1295. Marco Polo returned to Italy after many years of exploration in China and brought the knowledge of woodblock print with him on his return.
  2. Through the publications of his protestant ideas, Martin Luther challenged the orthodox practices and rituals of the Roman Catholic Church. He wrote 95 theses criticizing many of the practices of the Roman Catholic Church. Luther’s writings were immediately reproduced in vast numbers and read widely. This led to a division within the church and to the beginning of the Protestant Reformation. He also translated the New Testament of which 5000 copies were sold within a few days. These could be impossible without the printing technology. Deeply grateful to the print, Luther said, “Printing is the ultimate gift of God and the greatest one.” This is the reason why Luther was in favor of print and spoke out in praise of it.
  3. The Roman Catholic Church had to face many dissents from the mid-16th century onwards. People wrote many books that interpreted God and the creation in their own ways or as they liked. Therefore, the church banned such books and kept a record of such banned books. It was called the Index of Prohibited Books.
  4. Gandhi considered that the liberty of speech, liberty of the press, and freedom of association were the three most powerful vehicles for expressing and cultivating public opinion. Therefore, he said the fight for Swaraj was a fight for liberty of speech, press, and freedom of association.

Question 2. Write short notes to show what you know about:

  1. The Gutenberg Press
  2. Erasmus’ idea of printed book
  3. The Vernacular Press Act

Answer:

  1. The Gutenberg Press:
    • The first printing press was developed by Johan Gutenberg in the 1430s.
    • It was a developed form of the olive and wine presses. By 1448 Gutenberg perfected this system. The lead molds were used for casting the metal types for the letters of the alphabet.
    • The first book he printed was the Bible.
    • He produced 180 copies of the Bible in 3 years, which was much faster by standards of the time, at the time.
  2. Erasmus’s Idea of Printed Book: Erasmus was a Latin scholar and a Catholic reformer. He criticized the printing of books. He thought that most of the books were stupid, ignorant, scandalous, raving, irreligious, and seditious. According to him, such books devaluate valuable books.
  3. The Vernacular Press Act: Modelled on the Irish Press Laws, it was passed in 1878. This law gave the government tyrannical rights to censor reports and editorials in the vernacular press. If a seditious report was published and the newspaper did not heed an initial warning, the press was seized and the printing machinery confiscated. This was a complete violation of the freedom of expression.

Question 3. What did the spread of print culture in nineteenth-century India mean to:

  1. Women
  2. The poor
  3. Reformers

Answer:

  1. Women: The spread of print culture in 19th century India benefited Indian women through learning and education.
    • The liberal families supported the education of women to study or read as they believed education and reading would make women perfect. There was also a negative side to the introduction of books where women were concerned.
    • Conservative Hindus believed that a literate girl would be widowed. Muslims feared that educated women would be corrupted by reading Urdu romances.
    • This led to the counter-reaction, as most of the oppressed women began to study and read books and learn writing in secrecy. Some literate women started to write books and their autobiographies.
    • Rashsundari Devi, a young married girl wrote her autobiography “Amar Jiban” which was published in 1876. Overall, the print culture in 19th century India helped in the spread of the feeling of self-reliance among Indian women.
  2. The Poor: The poor people benefited from the spread of print culture because of the availability of books at a low price. The readership among them increased due to the publication of low-priced books.
    • Public libraries were also set up in the early 19th century, expanding access to books where all people could gain knowledge.
    • Encouraged and inspired by the social reformers, people like factory workers too set up their libraries and some even wrote books. Kashibaba, a Kanpur mill worker wrote and published ‘Chote aur Bade Ka Sawal’.
  3. Reformers: Indian reformers of the 19th century utilized print culture as the most potent means of spreading their reformist ideas and highlighting unethical issues.
    • They began publishing various vernacular, English, and Hindi newspapers, and books through which they could spread their opinions against widow immolation, child marriage, monotheism, Brahmanical priesthood, and idolatry to the common people of the country.
    • In this way, the spread of print culture in the 19th century provided them a space for attacking religious orthodoxy and spreading modern social and political ideas to people of different languages across the country.

Question 4. Why did some people in eighteenth-century Europe think that print culture would bring enlightenment and end despotism?

Answer:

Many people in eighteenth-century Europe thought that the print culture had the power in to bring enlightenment and end despotism.

This would help in spreading literacy and knowledge among all classes of people.

Social reformers like Louise, Sebastian Mercier, and Martin Luther felt that the print culture was the most powerful engine of progress and public opinion and hence, it would definitely bring enlightenment and an end to despotism.

Question 5. Why did some people fear the effect of easily available printed books? Choose one example from Europe and one from India.

Answer:

Some people especially from the upper class and the powerful class feared the effect of easily available printed books.

Their cause of fear was that due to the spread of literacy among the common people they could lose their position or authority.

Some people feared that this could lead to the spread of rebellions and irreligious thoughts. For example:

  • In Europe, the Roman Catholic Church tried to curb printed books through the Index of Prohibited Books.
  • In India, the Vernacular Press Act imposed restrictions on the Indian press and various local newspapers. Also, some religious leaders and some people from the upper castes expressed their fear.

Question 6. What were the effects of the spread of print culture on poor people in nineteenth-century India?

Answer:

The effects of the spread of print culture on poor people in nineteenth-century India were:

  1. The poor people benefited from the spread of print culture in India on account of the availability of low-price books and public libraries.
  2. Enlightening essays were written against caste discrimination and its inherent injustices. These were read by the people across the country.
  3. With the encouragement and support of social reformers, overworked factory workers set up libraries for self-education, and some of them even published their own work, for example, Kashibaba published his “Chhote Aur Bade Ka Sawal”.

Question 7. Explain how print culture assisted the growth of nationalism in India.

Answer:

The print culture immensely helped in the growth of nationalism in India in the following ways:

  1. Through the vernacular press, oppressive methods of colonial rule were reported.
  2. The misrule of the government and its initiative to curb the freedom of the press spread the nationalist ideas that demanded freedom of the press.
  3. Nationalist feelings and revolutionary ideas were secretly spread by the dailies such as The Amrit Bazar Patrika, The Indian Mirror, Kesri, The Hindu, Bombay Samachar, etc. Through these newspapers, national leaders always tried to mobilize public opinion of the Indian masses and unite them for the cause of nationalism.
  4. The print culture helped in educating the people who then started to be gradually influenced by the reformist and nationalist ideas of the various Indian leaders like Raja Ram Mohan Roy, Bal Gangadhar Tilak, Subhash Chandra Bose, M.K. Gandhi, etc.

Chapter 7 Print Culture And The Modern World Short Questions And Answers

Question 1. Who were the people who employed scribes to write in the 14th century?

Answer:

As handwritten books were expensive, only the rich, the aristocrats, and the Church could employ scribes. The scribes wrote only for aristocratic circles and rich monastic libraries.

With the coming of woodblock printing, merchants and traders started buying books in large numbers, with the result that booksellers could afford to hire scribes.

One bookseller could employ 50 scribes due to the new technology in printing. It was no longer the monopoly of the rich and the influential.

Read and Learn More Class 10 Social Science Solutions

Question 2. State the limitations of handwritten books.
Or
Why were manuscripts not used widely in everyday life before the age of print in India?

Answer:

Handwritten books were expensive and took a long time to produce. Copying was expensive, and it was a hard and laborious work.

The manuscripts were very fragile and could easily be spoilt. They were awkward in size and difficult to carry. The result was that their circulation was limited. Middle-class people could not afford them.

Question 3. Write a short note on the developments or innovations in printing technology in the 19th century.
Or
State three methods by which printed books became more accessible to people.

Answer:

  1. There was a series of innovations in the printing technology in the 19th century.
  2. Richard M. Hoe of New York perfected the power-driven cylindrical press. He could print 8,000 sheets per hour. His press was very useful for printing newspapers.
  3. The late 19th century saw the development of the offset press capable of printing six colours at a time.
  4. Electrically-operated press in the early 20th century increased the rate of printing operations.
  5. Methods of feeding paper improved, the quality of plates became better, machines were fed automatic paper reels, and photoelectric controls of the color register were introduced.

Question 4. Explain any three features of manuscripts before the age of print in India.

Answer:

  1. Manuscripts were copied on palm leaves or handmade papers.
  2. The pages were beautifully illustrated.
  3. They were pressed between wooden covers or sewn together to ensure preservation.
  4. They were available in vernacular languages. They were highly expensive and fragile.
  5. They could not be read easily as the script was written in different styles.
  6. They were not widely used in everyday life.

Question 5. Why did the woodblock method become popular in Europe?

Answer:

  1. Production of handwritten manuscripts could not meet the ever-increasing demand for books.
  2. Copying was an expensive, laborious, and time-consuming business.
  3. The manuscripts were fragile, awkward to handle, and could not be carried
    around or read easily.
  4. By the early 15th century, woodblocks started being widely used in Europe to print textiles, playing cards, and religious pictures with simple, brief texts.

Question 6. What was the role of new visual image culture in printing in India?

Answer:

  1. At the end of the 19th century, a new visual culture started.
  2. With the increasing number of printing presses visual images could be easily reproduced in multiple copies.
  3. Painters like Raja Ravi Verma produced images for mass circulation.
  4. Cheap prints and calendars were brought even by the poor to decorate the walls of their houses.

Question 7. Print popularised the ideas of the Enlightenment thinkers. Explain.

Answer:

  1. Collectively the writings of thinkers provided a critical commentary on tradition, superstition, and despotism.
  2. Scholars and thinkers argued for the rule of reason rather than custom and demanded that everything should be judged through the application of reason and rationality.
  3. They attacked the sacred authority of the church and the despotic power of the state thus eroding the legitimacy of a social order based on tradition.
  4. The writings of Voltaire and Rousseau were read widely and those who read these books saw the world through new eyes, eyes that were questioning, critical, and rational.

NCERT-Solutions-For-Class-10-History-Chapter-7-Print-Culture-And-The-Modern-World

Question 8. Why was China a major producer of printed material for a long time?

Answer:

China had a huge bureaucratic system. The personnel for this system was chosen based on a Civil Service Examination.

To help the candidates, textbooks for this examination were printed in enormous numbers. In the 16th century, when more candidates were recruited, more printed material appeared in public.

Question 9. Write briefly why some people feared that the development of print could lead to the growth of dissenting ideas.

Answer:

With the coming of printing technology, there was a greater possibility for wide circulation of ideas. A new world of debate and discussion would be created.

Those who did not agree with the established norms were now able to publish and circulate their ideas.

Through print media, they persuaded people to think differently and developed the spirit of inquiry. The growth in popularity of the Reformist ideas in Europe is an example of this trend.

Question 10. Write a short note on how the printing press came to India.

Answer:

The printing press was brought to India by the Jesuit missionaries. They came to Goa in the 19th century, learned Konkani, and printed many tracts.

But in 1674, about 50 books were printed in Konkani and Kanarese languages. The Catholic priests published the first book in Tamil in 1579, in Cochin and in 1713 the first book in Malayalam was printed by them.

The Dutch Protestant missionaries had already printed 72 Tamil books by 1710, most of them were translations of earlier texts. By the end of the 18th century, newspapers began to appear in various Indian languages.

Question 11. What were the difficulties faced by the manuscripts in India?

Answer:

The handwritten books were very expensive and very fragile. They were difficult to carry and had to be handled carefully.

They were also not easy to read as the script was written in many styles. Because of this difficulty, they were not widely read. Teachers dictated them from memory and the students wrote them down.

Students learned not to read the manuscripts but only write them. Though in the pre-colonial period, Bengal had many village primary schools, the manuscripts were not used in everyday life.

Thus, students became literate without ever actually reading the texts.

Question 12. “The print culture created the conditions within which the French Revolution occurred.” Support the statement by giving three arguments.
Or
Why do some historians think that the print culture created the basis for the French Revolution?

Answer:

  1. Print popularised the ideas of enlightened thinkers, and the writings of Voltaire and Rousseau were read widely.
    • They made a critical commentary on tradition, superstition, and despotism. It opened the eyes of the readers and made them question, be critical, and rational.
  2. Print created a new culture of dialogue and debate. All values, norms, and institutions were revalued and discussed by a public that had become aware of the power of reason. New ideas of social revolution came into being.
  3. By the 1780s, there was an outpouring of literature, that mocked royalty and criticized their morality. In the process, it raised questions about the existing social order.
    • It led to hostile sentiments against the monarchy. Thus, the print culture created the conditions in which the French Revolution occurred.

Question 13. Who were the supporters of women’s education in India and why?

Answer:

The print culture affected the lives of women. Not only women readers but also many women writers came forward to write about women’s experiences.

They were supported by liberal fathers and husbands who started educating their womenfolk at home. Some even sent them to schools.

Many schools for women were set up by social workers and rich people in towns and cities. Many reformers also supported education among women.

Question 14. What was the role of cartoons and caricatures in new forms of publications?

Answer:

By the 1870s, cartoons and caricatures appeared in many journals and newspapers. They commented on social and political issues.

By making fun of certain beliefs, they aroused the public and made them think about certain rules of society and the role of imperial rulers.

Some caricatures made fun of the educated Indians’ fascination for everything Western in tastes, clothes, etc. Some, on the other hand, expressed fear of change of any kind.

In the field of politics, they lampooned the behavior and attitude of imperial rulers. The imperial rulers returned the compliment by making fun of and caricaturing the nationalists.

Question 15. Explain how print culture had assisted the growth of nationalism in India in the 19th century.

Answer:

  1. Print culture led to the publication of most papers in Vernacular languages. Many more journals were published after 1870.
  2. These journals and newspapers published cartoons and caricatures criticizing imperial rule and commenting on social and political issues.
    • The vernacular newspapers like Tilak’s Kesari and Maratha became assertively nationalist and reported on colonial misrule and encouraged nationalism.
  3. The repressive measures passed by the British government provoked militant protest. Tilak was imprisoned for writing about them in his Kesari, in 1908.
    • It led to widespread protests. Print helped the leaders to carry their ideas to people across India, brought them closer, and helped the growth of nationalism.

Question 16. How did print culture affect women in nineteenth-century India? Explain.

Answer:

Women became important as readers as well as writers. The lives and feelings of women began to be written in vivid and intense ways. The number of women readers increased enormously in middle-class homes.

Liberal fathers and husbands began educating their womenfolk at home and sent them to schools when schools for women were set up in cities and towns.

Many journals carried a syllabus and attached suitable reading matter which could be used at home.

From the 1860s, a few Bengali women like Kailashbashini Debi wrote books highlighting the experience of women who were imprisoned, kept in ignorance forced to do hard domestic work, and treated unjustly.

Tarabai Shinde and Pandita Ramabai of Maharashtra in 1880, wrote with anger about the miserable lives of upper-caste Hindu women – especially widows.

In Central Calcutta, an entire area called Battala was devoted to printing popular books, profusely illustrated. They were carried by pedlars to homes enabling women to read them in their leisure time.

But everyone was not so liberal. Hindus (conservative) believed that a literate girl would become a widow.

Muslims believed that an educated woman would be corrupted by reading. Some women had to learn to read and write in secret, like Rashsundari Debi of East Bengal.

She learned to read secretly in her kitchen and later wrote her autobiography Amar Jiban in 1876.

Question 17. Explain the main features of the first printed Bible.

Answer:

The main features of the first printed Bible were:

  • About 180 copies of the Bible were printed and it took three years to produce them.
  • The text was printed in the New Gutenberg press with metal type, but the borders were carefully designed, painted, and illuminated by hand by artists.
  • No two copies were the same. Every page of each copy was different. This made everyone possess a copy that they could claim was unique.
  • Colour was used within the letters in various places. This had two functions, i.e., it added color to the page and highlighted all the holy words to emphasize their significance. Color on every page was added by hand.
  • Gutenberg printed the text in black leaving spaces where the color could be filled later.

Question 18. Examine the role of missionaries in the growth of the press in India.

Answer:

The printing press first came to India with Portuguese missionaries to Goa in the mid-sixteenth century. Jesuit priests learned Konkani and printed several tracts.

By 1674, about 50 books were printed in Konkani and Kanara languages. Catholic priests published the first Tamil book in 1579 at Cochin and in 1713, the first Malayalam book was published by them.

By 1710, Dutch Protestant missionaries published 32 Tamil Texts, many of them translations of older works.

Question 19. What role was played by the print culture in bringing the French Revolution?

Answer:

Role of print culture in bringing French Revolution:

  1. Print popularised the ideas of Enlightenment thinkers. Collectively, their writing provided a critical commentary on tradition, superstition, and disposition. They argued for the rule of reason rather than custom.
  2. They attacked the sacred authority of the Church and the despotic power of the state. This eroded the authority of a social order based on tradition.
    • The writings of Voltaire and Rousseau made readers see the world through new eyes, eyes that questioned and were rational and critical.
  3. Print created a new culture of dialogue and debate. Now all values, norms, and institutions were re-evaluated and discussed by the public, now aware of their power to question existing beliefs and ideas. It led to new ideas of social revolution.
  4. By the 1780s there was an output of literature that mocked royalty and questioned their morality. Cartoons and caricatures presented a monarchy interested only in their own pleasures, while the ordinary people suffered immense hardships.
  5. Literature spread hostile sentiments against the monarchy, though it was circulated underground. But we must remember that to combat the above ideas was the influence of the Church.
    • If people read Voltaire and Rousseau, they were also exposed to monarchical and Church propaganda. So print did not directly shape their minds, but it made it possible for people to think differently.

Question 20. How did the printing press bring forth changes in reading culture?

Answer:

With the printing press, a new reading public emerged.

  1. Printing reduced the cost of books.
  2. The time and labor to produce each book came down. Multiple copies could be produced easily.
  3. Books flooded the market, reaching out to an evergrowing readership.
  4. It created a new culture of reading.
  5. Common people could not read books earlier, only the elite could. Common people heard a story or saw a performance collectively.
  6. Instead of a hearing public now there was a reading public.
  7. The rate of literacy in European countries was also low till the 20th century. Publishers reached out to people by making them listen to books being read out.
  8. Printers published popular ballads and folktales, profusely illustrated. These were then sung and recited at village gatherings in taverns in towns.
  9. Oral culture thus entered print and printed material was orally transmitted. Hearing and reading the public, thus became one.

Question 21. Why were the printed books popular even among the illiterate people?

Answer:

  1. First, very cheap small books brought to markets in 19th-century towns allowed poor people traveling, to buy them. Public libraries set up in the early 20th century expanded the access to books.
  2. From the late 19th century, many social reformers like Jyotiba Phule (a Maratha reform pioneer) wrote about injustices of the caste system in their books (Gulamgiri, 1871).
    • In the 20th century, B.R. Ambedkar and E.V. Ramaswamy Naicker wrote powerfully on caste, and their books were read by people all over India.
    • Print Culture and the Modern World Workers in factories were too overworked and lacked education to write much about their experiences.
    • A Kanpur mill worker wrote and published “Chhote Aur Bade Ka Sawal” in 1938.
    • To show links between caste and class exploitation under the name of Sudarshan Chakhar between 1935 and 1955 were together published and were called “Sacchi Kavitayen”.
    • Libraries were set up in Bangalore Cotton Mills and in Bombay. It was done to bring literacy and to propagate the message of nationalism. The printed books made the poor crazy about reading.

Question 22. Describe the progress of Printing in Japan.

Answer:

Buddhist Missionaries from China introduced hand-printing technology into Japan around C.E. 768-770.

The oldest Japanese book, printed in C.E. 868, is the Buddhist Diamond Sutra, containing six sheets of text and woodcut illustrations. Pictures were printed on textiles, playing cards, and paper money.

In medieval Japan, poems and prose writings were regularly published, and books were cheap and in plenty.

In the late 18th century, flourishing urban circles in Edo (modern Tokyo) published illustrated collections by printing artists.

Courts and bookstores were packed with hand-printed material of various types books on women, musical instruments, calculations, tea ceremonies, flower arrangements, proper etiquette, cooking, and famous places.

Famous examples: Kitagawa Utamoro’s contribution to an art form called Ukiyo (pictures of the floating world).

Question 23. What is a manuscript? Write four shortcomings of manuscripts.

Answer:

A manuscript is a handwritten book. It was written on a palm leaf or on a handmade paper. Pages were sometimes beautifully illustrated.

They would be either pressed between wooden covers or sewn together to ensure preservation.

The four shortcomings of manuscripts were:

  1. They were highly expensive and fragile.
  2. They had to be handled carefully.
  3. They could not be read easily as the script was written in different styles.
  4. So they were not widely used. Students very often did not read the texts. They only learned to write.
    • Teachers dictated portions from memory and students wrote them down. Many became literate without ever actually reading any kind of text.

Question 24. What was the attitude of people in India in the nineteenth century towards women reading? How did women respond to this?

Answer:

There was not a universally favorable attitude. Conservative Hindus believed that a literate girl would be widowed and Muslims feared educated women would be corrupted by reading Urdu romances.

Rebel women defied such prohibition. A Muslim girl in north India defied her family and secretly learned to read and write Urdu.

Rashsundari Debi, a young married girl in a very orthodox family, learned to read in the secrecy of her kitchen. Later she published her autobiography in Bengali.

A few Bengali women like Kailash Bashini Debi wrote books highlighting the experiences of women. In the 1860s, Tarabai Shinde and Pandita Ramabai of Maharashtra wrote about the miserable lives of upper-caste women.

Women writing in Tamil expressed their gratitude to books. The attitude in general was to keep women imprisoned at home, ignorant, forced to do hard domestic work, and subject to unfair treatment.

In Punjab, folk literature exhorted women to be obedient wives (Ram Chaddha’s Istri Dharm Vichar.) The Khalsa Tract Society published cheap booklets with the same message.

In Bengal, – an entire area in Central Calcutta the Battala was devoted to printing popular books. They were cheap editions of religious texts, scriptures as well as scandalous literature.

Women’s education was not encouraged by the majority as Begum Rokeya Sakhawat Hossain reported in her address to Bengal Women’s Educated Conference.

Question 25. Explain the role played by print in bringing about a division in the Roman Catholic Church.

Answer:

In 1517, a religious reformer, Martin Luther, wrote 95 theses criticizing many practices and rituals of the Roman Catholic Church. A printed copy of this was posted on a Church door in Wittenberg.

It challenged the Church to debate his ideas. Luther’s writings were reproduced in vast numbers and read widely. This led to a division within the Church and to the beginning of the Protestant Reformation.

Luther’s translation of the Bible sold 5,000 copies in the first week and soon the second edition began.

The print of his theses, according to scholars, brought about a new intellectual atmosphere and spread rapidly the ideas of Reformation.

Question 26. State three ways in which early printed books closely resembled manuscripts.

Answer:

  1. The metal letters imitated the ornamental handwritten styles.
  2. Borders were illuminated by hand with foliage and other patterns.
  3. Illustrations were printed. In the books meant for the rich, space for decoration was kept blank on the printed page. Each purchaser could choose the design and decide on the painting school that would do the illustrations.

Question 27. How did print help connect communities and people in different parts of India? Explain with examples.

Answer:

Print connected communities and people in different parts of India through newspapers, by encouraging public debates on important issues.

New ideas emerged in Sambad Kaumudi published by Raja Ram Mohan Roy in 1821, which provoked debate on widow immolation, Brahmanical priesthood, idolatry, etc., by printing ideas in every language spoken by ordinary people.

In retaliation, Hindu orthodoxy started Samachar Chandrika to oppose his opinions. In north India, ulemas feared colonial rulers would change Muslim personal laws, published Persian and Urdu translations of holy scriptures, and printed religious newspapers and tracts.

The Deoband Seminary published thousands of fatwas telling Muslim readers how to conduct themselves in their everyday lives and explaining Islamic doctrines.

Hindus also published religious texts in Vernacular languages. Ramcharitmanas of Tulsidas came out in Calcutta in 1810.

Naval Kishore Press at Lucknow and Shri Venkateshwar Press in Bombay published numerous religious texts in Vernacular languages.

The religious texts reached a very wide circle of people encouraging discussions, debates, and controversies within and among different religions.

Newspapers conveyed news from one place to another, creating pan-Indian identities. Thus, print not only stimulated the publication of conflicting opinions but also connected communities and people in different parts of India.

Question 28. Why did the new technology not entirely displace the existing art of producing books by hand?

Answer:

  1. The printed books closely resembled the written manuscripts in appearance and layout.
  2. The metal letters imitated the ornamental hand styles.
  3. Borders in printed books were illuminated by hand with foliage and other patterns and illustrations were painted.
  4. In the books for the rich, space for decoration was kept blank on the printed page. After each purchaser had chosen the design, the painting school would do the illustrations.

So, new technology did not entirely displace the existing art of producing books by hand.

Question 29. By the end of the 19th century, a new visual culture was taking shape. Explain.

Answer:

The setting up of an increasing number of printing presses made it easy to reproduce visual images in multiple copies. Painters like Raja Ram Varma produced images for mass circulation.

Cheap prints and calendars could be bought by the poor to decorate the walls of their homes or places of work.

The prints began shaping popular ideas about modernity and tradition, religion and politics, society and culture. In the 1870s, caricatures and cartoons were published in journals and newspapers.

Imperial cartoons lampooned nationalists and nationalist cartoons criticized the imperial rule.

Question 30. How did ideas about science, reason, and rationality find their way into popular literature in 18th-century Europe?

Answer:

In the 18th century the periodical press combined information about current affairs with entertainment. Newspapers and journals carried information about wars and trade as well as news of developments in other places.

Similarly, the ideas of philosophers now became accessible to common people. Ancient and medieval scientific texts were compiled and published, and maps and scientific diagrams were widely printed.

When scientists like Sir Isaac Newton began to publish their discoveries, they could influence a much wider circle of scientifically minded readers.

The writings of thinkers such as Thomas Paine, Voltaire, and Rousseau were also widely printed and read. Thus their ideas of science, reason, and rationality found their way into popular literature.

Question 31. How did the uses of printing diversify in China by the 17th century? Explain.

Answer:

By the 17th century, urban culture bloomed in China, and the use of printing diversified.

  1. Printing was no longer used just by scholars and officials.
  2. Merchants used print in their everyday life, as they collected trade information.
  3. Reading increasingly become a leisure activity. New readers preferred narratives, poetry, autobiographies, anthologies of literary masterpieces, and romantic plays.
  4. Rich women began to read, many women began publishing their poems and plays. Wives of scholar-officials published their work and courtesans wrote about their lives.

Question 32. Write the name of any two women writers of India in the 19th century and highlight the contribution of anyone who wrote about the different experiences of the women.

Answer:

The two women writers of India in the 19th century were:

  1. Kailash Bashini Debi
  2. Tarabai Shinde

Kailash Bashini Debi was a Bengali writer who wrote books, highlighting the experiences of women. She wrote about how women were imprisoned at home, kept in ignorance, forced to do hard domestic work, and treated unjustly.

Question 33. How did printing come to Europe from China? Explain.

Answer:

In 1295, Marco Polo a great explorer returned to Italy after years of exploration in China. Marco Polo brought the knowledge of woodblock printing from China and soon Italians began producing books with woodblocks.

The technology spread rapidly to the rest of Europe. Merchants and students in the university started buying cheaper printed copies.

Question 34. Discuss the growth of printing presses in Europe from the 15th to the 16th century.

Answer:

In 100 years (1450-1550), the print culture had spread from Germany to all over Europe. Printers from Germany traveled all over Europe looking for jobs.

They set up presses in most European countries. By 1470, Rome, France, and Holland had printing presses. In the second half of the 15th century, 20 million books were printed.

By the end of the 16th century, there were 200 million printed copies flooding Europe.

Chapter 7 Print Culture And The Modern World Multiple Choice Questions And Answers

Question 1. Printing was first developed in

  1. Japan
  2. Portugal
  3. China
  4. Germany

Answer: 3. China

Question 2. Which one among the following is an ancient name of Tokyo?

  1. Osaka
  2. Nagano
  3. Edo
  4. Gifu

Answer: 3. Edo

  1. Question 3. The first printed book by the mechanical press was ___________.
    Or
    Which of the following was the first book printed by Gutenberg?The New Testament
  2. The Bible
  3. Chap Books
  4. Diamond Sutra

Answer: 2. The Bible

Question 4. Who brought printing to Europe?

  1. Martin Luther
  2. Gutenberg
  3. Marco Polo
  4. Erasmus

Answer: 3. Marco Polo

Question 5. “Printing is the ultimate gift of God and the greatest one”. Who spoke these words?

  1. Johann Gutenberg
  2. Newcomen
  3. Mahatma Gandhi
  4. Martin Luther

Answer: 4. Martin Luther

Question 6. Who developed the first printing press in the 1430s?

  1. Marco Polo
  2. Johann Gutenberg
  3. James Watt
  4. None of the above

Answer: 2. Johann Gutenberg

Question 7. The British imposed the Vernacular Press Act

  1. To curb internal revolts
  2. To curtail rising discontentment among Indians
  3. To promote Indian allegiance to the British
  4. To confiscate the property of the Indian Press

Answer: 2. To curtail rising discontentment among Indians

Question 8. Choose the name of the oldest printed book in Japan.

  1. Diamond Sutra
  2. The Bible
  3. Ukiyo
  4. The Koran

Answer: 1. Diamond Sutra

Question 9. Which of the following books reflects the plight of the ‘lower castes’ and the poor in India?

  1. Gulamagiri
  2. Chhote Aur Bade Ka Sawal
  3. Sachchi Kavitayan
  4. All of the above

Answer: 4. All of the above

Question 10. In India, the printing press first came to

  1. Goa with Portuguese
  2. Bombay with British
  3. Goa with British
  4. Bombay with Portuguese

Answer: 1. Goa with Portuguese

Question 11. Who among the following was scared of print?

  1. Writers and philosophers
  2. Religious authorities and monarchs.
  3. Common people – including peasants, workers, poor women, etc.
  4. Printers and Publishers

Answer: 2. Religious authorities and monarchs.

Question 12. Which one among the following is an autobiography of Rashsundari Devi?

  1. Amar Jiban
  2. Amar Jyoti
  3. Amar Jawan
  4. Amar Zindagi

Answer: 1. Amar Jiban

Question 13. Who among the following introduced hand-printing technology in Japan?

  1. Buddhist Missionaries from India
  2. Buddhist Missionaries from Japan
  3. Buddhist Missionaries from China
  4. None of the above

Answer: 3. Buddhist Missionaries from China

Question 14. The first weekly paper published in India was:

  1. Bombay Samachar
  2. Bengal Gazette
  3. Shamsul Akbar
  4. Samachar Chandrika

Answer: 2. Bengal Gazette

Question 15. The newspaper started by Bal Gangadhar Tilak was:

  1. The Kesari
  2. The Hindu
  3. The Statesman
  4. The Tribune

Answer: 1. The Kesari

1. Passage Based Questions And Answers

Read the passage given below and answer the questions that follow:

Thomas Wood, a Yorkshire mechanic, narrated how he would rent old newspapers and read them by firelight in the evenings as he could not afford candles. Autobiographies of poor people narrated their struggle to read against grim obstacles.

Read the excerpt given above and answer the following questions:

  1. Who was Thomas Wood?
  2. What does this passage depict?
  3. What were the major obstacles poor people faced in reading newspapers?

Answer:

  1. Thomas Wood was a mechanic. He lived in Yorkshire.
  2. This passage depicts the desire of poor people to read Newspapers. By reading newspapers, they wanted to overcome different obstacles.
  3. The major obstacle, they faced was that they could not buy newspapers. They often rented old newspapers to read.

2. Oral Quiz

  1. Skilled Handwriters were called
  2. Who said that the printing press was the most powerful engine to progress?
  3. She is the author of Amar Jiban
  4. British introduced the Vernacular Press Act to
  5. Ancient manuscripts were written on

Answer:

  1. Scribes
  2. Mercier
  3. Rash Sundari Devi
  4. Suppress the freedom of the Press
  5. Palm leaves

3. Matching of Columns

NCERT Solutions For Class 10 Social Science History Chapter 7 Print Culture and The Modern World Match The Column

Answer:

1.-(d) 2.-(a) 3.-(b) 4.-(e) 5.-(c)

Important Questions for CBSE Class 12 Physics Chapter 11 Dual Nature of Radiation and Matter

CBSE Class 12 Physics Chapter 11  Dual Nature Of Radiation And Matter Multiple Choice Questions And Answers

Important Questions for CBSE Class 12 Physics Chapter 11 Dual Nature of Radiation and Matter

Question 1. The speed acquired by a free electron when accelerated from rest through a potential difference of 100V is:

  1. 6 x 106 m s-1
  2. 3 x 106 m s-1
  3. 4 x 105 m s-1
  4. 2 x 103 m s-1

Answer: 1. 6 x 106 m s-1

Read and Learn More Important Questions for Class 12 Physics with Answers

Question 2. Photons of energy 1 eV and 2.5 eV successively illuminate a metal whose work function is ________.

  1. 1:2
  2. 2:1
  3. 3:1
  4. 1:3

Answer: 1. 1:2

K.Emax for 1 photon = 1-0.5 = 0.5eV

K.Emax for 2 photon = 2.5-0.5 = 2eV

⇒ \(\frac{K E_1}{K E_2}=\frac{0.5}{2}=\frac{1}{4} \quad\left(K=\frac{1}{2} m v^2\right)\)

So speed \(\left(\frac{v_1}{v_2}=\frac{1}{2}\right)\)

Question 3. The de-Broglie wavelength associated with a particle with rest mass m0 and moving with the speed of light in vacuum is ________.

  1. \(\frac{\mathrm{h}}{\mathrm{m}_0 \mathrm{c}}\)
  2. 0
  3. \(\frac{\mathrm{m}_0 \mathrm{c}}{\mathrm{h}}\)

Answer: 2. 0

Question 4. Photoelectric effect represents __________

  1. Electron has a wave nature
  2. Light has a particle nature
  3. Light has a wave nature
  4. None of these

Answer: 2. Light has a particle nature

Question 5. If the momentum of an electron is required to be the same as that of a wave having 5200 Å wavelength, its velocity should be ______ ms-1

  1. 103
  2. 1.4 x 103
  3. 1.39 x 103
  4. 2.8 x 103

Answer: 3. 1.39 x 103

⇒ \(\lambda=\frac{h}{m v}\)

∴ \(v=\frac{h}{m \lambda}=\frac{6.62 \times 10^{-34}}{9.1 \times 10^{-31} \times 5200 \times 10^{-10}}=1.39 \times 10^3 \mathrm{~m} / \mathrm{s}\)

Question 6. To increase the de Broglie wavelength of an electron from 0.5 x 10-10 m to 10-10 m, its energy should be _________.

  1. Increased to four times
  2. Halved
  3. Doubled
  4. Decreased to the fourth part

Answer: 4. Decreased to fourth part

⇒ \(\lambda=\frac{\mathrm{h}}{\sqrt{2 \mathrm{mK}}}\) ⇒ \(\lambda \propto \frac{1}{\sqrt{\mathrm{K}}}\)

∴ \(K \propto \frac{1}{\lambda^2}\)

λ → twice, K must be \(\left(\frac{1}{4}\right)^{th}\)

Question 7. The energy of the photon is E = hf and its momentum is \(P=\frac{h}{\lambda}\), where λ, is the wavelength of the photon with this assumption speed of the light wave is

  1. \(\frac{P}{E}\)
  2. \(\frac{E}{P}\)
  3. EP
  4. \(\left(\frac{E}{P}\right)^2\)

Answer: 2. \(\frac{E}{P}\)

⇒ \(E=h f=\frac{h c}{\lambda}\)

⇒ \(c=\frac{E \lambda}{h} \quad\left(\frac{\lambda}{h}=\frac{1}{P}\right)\)

∴ \(c=\frac{E}{P}\)

Question 8. Which of the following physical quantities has the dimension of Planck constant (h)?

  1. Angular momentum
  2. Force
  3. Energy
  4. Power

Answer: 1. Angular momentum

Question 9. If the photoelectric effect is not seen with the ultraviolet radiations in a given metal, photoelectrons may be emitted with the _________.

  1. Radio waves
  2. Infrared waves
  3. X-rays
  4. Visible light

Answer: 3. X-rays

Question 10. The work function of _______ is the lowest.

  1. Platinum
  2. Caesium
  3. nickel
  4. Copper

Answer: 2. Caesium

Question 11. The value of slopping potential depends on ________ of incident light.

  1. Intensity
  2. Frequency
  3. Momentum
  4. Velocity

Answer: 2. Frequency

Question 12. Monochromatic light of frequency 6 x 1014 Hz is produced by laser. Each photon has an energy = ________ J.

  1. 6 x 1014
  2. 4 x 10-19
  3. 4 x 10-20
  4. 6 x 10-14

Answer: 2. 4 x 10-19

E = hv

E = 6.62 x 10-34 x 6 x 1014 = 39.72 x 10-20 = 3.972 x 10-19 = 4 x 10-19 J

Question 13. For a given frequency of incident radiation, slopping potential ________.

  1. Does not depend on the intensity
  2. Is inversely proportional to the intensity
  3. Is directly proportional to the intensity
  4. Is inversely proportional to the square of intensity.

Answer: 1. Does do not depend on the intensity

Question 14. The slope of a graph of stopping potential versus frequency of incident radiation is _________.

  1. c
  2. h
  3. \(\frac{h}{e}\)
  4. \(\frac{e}{h}\)

(where h = Planck’s constant and e = charge of an electron)

Answer: 3. \(\frac{h}{e}\)

Question 15. De-Broglie wavelength of a bullet of mass 0.040 kg travelling at the speed of 1 km/s is _________ m.

  1. 1.7 x 10-35
  2. 4.04 x 10-24
  3. 1. 1 x 10-32
  4. 3 x 10-32

Answer: 1. 1.7 x 10-35

∴ \(\lambda=\frac{h}{m v}=\frac{6.62 \times 10^{34}}{0.040 \times 1000}=1.655 \times 10^{-35}=1.7 \times 10^{-35} \mathrm{~m}\)

CBSE Class 12 Physics Chapter 11  Dual Nature Of Radiation And Matter Assertion And Reason

For question numbers 1 to 6 two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (1), and (2). (3) and (4) as given below.

  1. Both A and R are true and R is the correct explanation of A
  2. Both A and R are true but R is NOT the correct explanation of A
  3. A is true but R is false
  4. A is false and R is also false

Question 1. Assertion: The photoelectric effect demonstrates the wave nature of light.

Reason: The number of photoelectrons is proportional to the frequency of light

Answer: 1. Both A and R are true and R is the correct explanation of A

Question 2. Assertion: At saturation, the photoelectric current is maximum.

Reason: At saturation, all the electrons emitted from the cathode can reach the anode.

Answer: 1. Both A and R are true and R is the correct explanation of A

Question 3. Assertion: A photon is not a material particle. It is a quantum of energy.

Reason: The photoelectric effect demonstrates the wave nature of radiation.

Answer: 3. A is true but R is false

Question 4. Assertion: Photo electric current increases if the distance between the cathode and anode is increased.

Reason: The momentum of a photon is directly proportional to its wavelength.

Answer: 4. A is false and R is also false

Question 5. Assertion: The photosensitivity of a metal is high if its work function is small.

Reason: Work function = hv0, where v0 is the threshold frequency.

Answer: 2. Both A and R are true but R is NOT the correct explanation of A

Question 6. Assertion: In his study of photoelectric emission, Hallwachs connected a negatively charged zinc plate to an electroscope. He found that negatively charged particles were emitted from the zinc plate under the action of visible light.

Reason: An uncharged zinc plate becomes positively charged when it is irradiated by visible light.

Answer: 4. A is false and R is also false

CBSE Class 12 Physics Chapter 11  Dual Nature Of Radiation And Matter Short Questions And Answers

Question 1. A proton and a particle are accelerated through the same potential difference. Which one of the two has

  1. Greater de-Broglie wavelength, and
  2. Less kinetic energy? Justify your answer

Answer:

∴ \(\lambda=\frac{h}{p}=\frac{h}{\sqrt{2 q V m}}\)

1. α – particle: \(\frac{h}{\sqrt{2 q_{\alpha} V_{m_{\alpha}}}}=\lambda_\alpha\) ( ∵ \(\begin{aligned} & \mathrm{q}_\alpha=2 \mathrm{q}_{\mathrm{p}}  & \mathrm{m}_{\mathrm{\alpha}}=4 \mathrm{~m}_{\mathrm{p}} \end{aligned}\))

proton: \(\frac{h}{\sqrt{2 q_p V m_p}}=\lambda_p\)

Clearly, \(\lambda_{\mathrm{p}}>\lambda_\alpha \text { as } \mathrm{m}_\alpha>\mathrm{m}_{\mathrm{p}} \ and \mathrm{q}_\alpha>\mathrm{q}_{\mathrm{p}}\)

So, a proton has a greater de-broglie wavelength.

2. As \(\frac{1}{2} m v^2=q_V ;(\text { K.E. })_{\mathrm{p}}<(\text { K.E. })_{\alpha} \text { as } \mathrm{q}_{\mathrm{p}}<\mathrm{q}_{\alpha}\)

So, a proton has less K.E

Question 2.

  1. Draw graphs showing the variation of photoelectric current with applied voltage for two incident radiations of equal frequency and different intensities. Mark the graph for the radiation of higher intensity.
  2. Name the phenomenon which shows the quantum nature of electromagnetic radiation.

Answer:

Dual Nature Of Radiation And Matter Variation Of Photoelectric Current

The graph I2 corresponds to radiation of higher intensity

2. Photoelectric effect (PEE)

Question 3. Plot a graph showing the variation of de-Broglie versus \(\frac{1}{\sqrt{V}}\) where V is accelerating the potential for two particles A and B carrying the same charge but of masses m1, m2, (m1 > m2). Which one of the two represents a particle of smaller mass and why?

Answer:

As, \({\lambda} =\frac{h}{\sqrt{2 \mathrm{mqV}}}\)

Graph: Slope of verses \(\frac{1}{\sqrt{V}}\) graph will be inversely prop, to the square root of the mass of the particles. Now, the slope of B is greater and it shows that its mass is smaller.

Dual Nature Of Radiation And Matter Variation Of De-Broglie Wavelength

Question 4. The wavelength λ of a photon and the de-Broglie wavelength of an electron have the same value. Show that the energy of a photon is (2λmc/h) limes the kinetic energy of electron: where m. c and h have their usual meaning.

Answer:

⇒ \(E_{\text {photon }}=\frac{h c}{\lambda}\) → (1) \(\lambda_{\text {photon }}=\lambda_{\text {electron }}={\lambda}\)

⇒ \(E_{\text {elcetron }}=\frac{h^2}{2 m \lambda^2}\) → (2) ( ∵ \(\lambda=\frac{\mathrm{h}}{\sqrt{2 \mathrm{mE}_{\text {electron }}}}\)))

Dividind (1) by (2), \(\frac{\mathrm{E}_{\text {photon }}}{\mathrm{E}_{\text {electron }}}=\frac{2 \mathrm{mc \lambda}}{\mathrm{h}}\)

Question 5. Calculate the dc-Broglic wavelength of the electron orbiting in the n = 2 stale of hydrogen atom.

Answer:

The velocity of an e in the first orbit (n = 1) of the hydrogen atom, v = 2.18 x 106 m/s.

Now, the velocity of e in the second orbit (n = 2) of the hydrogen atom will be given as, v’ = v/n

∴ v’ = 1.09 x 106 m/s

So mv’ = 9.9 x 10-25

Putting the values in \(\lambda=\mathrm{h} / \mathrm{mv}^{\prime}=\frac{6.6 \times 10^{-34}}{9.9 \times 10^{-25}}=6.68 Å\)

Question 6.

  1. Define the intensity of radiation based on a photon picture of light. Write its S.I. unit.
  2. Draw a plot showing the variation of the de-Broglie wavelength of an electron as a function of its K.E.

Answer:

The intensity of radiation is defined as the energy associated with several photons incident/could from a unit surface area in unit time.

i.e. \(\text { Intensity }=\frac{\text { Energy }}{\text { Area } \times \operatorname{time}}\)

SI unit:

∴ \(\frac{\text { joule }}{m^2-s} \text { or } \mathrm{W}-\mathrm{m}^{-2}\)

Dual Nature Of Radiation And Matter A Plot

∵ \(\lambda=\frac{\mathrm{h}}{\sqrt{2 \mathrm{mE}}}\)

Question 7.

  1. Name the factor on which photoelectric emission from a surface depends.
  2. Define the term ’threshold frequency’ for a photosensitive material.

Answer:

  1. Metal should be photo-sensitive.
  2. For a given photosensitive material, threshold frequency is the minimum frequency of radiation that is required for photoelectric emission from the material.

Question 8.

  1. Plot a graph showing the variation of photocurrent v/s collector potential for three different intensities I1 < I2 < I3, two of which (I1 and I2) have the same frequency v and the third has frequency v1 > v2.
  2. Explain the nature of the curves based on Einstein’s equation.

Answer:

Dual Nature Of Radiation And Matter Variation Of Photo Current

2. From. eV0 = hv- hv0 [Clearly stopping potential (V0) depends on incident freq.(v)]

or \(V_0=\frac{h}{e} v-\frac{h}{e} v_0\)

So. for I1 and I2 intensities, freq. (v) is the same, hence for them stopping potential (V0) is also equal.

Further, for. intensity having freq (v1) stopping potential is more. (∵ V1 > V2 )

Question 9. For the light of wavelength 400 nm incident on the cathode of a photocell, the stopping potential is 6V. If the wavelength of incident light is increased to 600 nm. calculate the new stopping potential. (Take h =4.14 x 10-15 eV. s)

Answer:

Given: \(\mathrm{hc}=4.14 \times 10^{-15} \times 3 \times 10^8 \mathrm{eV}s . \frac{\mathrm{m}}{\mathrm{s}}=12.42 \times 10^{-7} \mathrm{eVm}=12420 \mathrm{eVA}\)

λ1= 400 nm, λ2= 600 nm

V01 =6V, V02 = ?

∵ E = W0 + K.Emax

K.Emax = E – W0

⇒ \(\mathrm{eV}_0=\frac{h \mathrm{c}}{\lambda}-\mathrm{W}_0\) → (1)

So, \(\mathrm{eV}_{01}=\frac{h c}{\lambda_{1}}-W_0\) → (2)

⇒ \(\mathrm{eV}_{02}=\frac{\mathrm{hc}}{\lambda_2}-\mathrm{W}_0\) → (3)

Equation (3) – (2)

⇒ \(\left(\mathrm{V}_{02}-\mathrm{V}_{01}\right) \mathrm{e}=\mathrm{hc}\left(\frac{\mathrm{I}}{\lambda_2}-\frac{1}{\lambda_1}\right) \Rightarrow\left(\mathrm{V}_{02}-6\right)=\frac{\mathrm{hc}}{\mathrm{e}}\left(\frac{1}{600}-\frac{1}{400}\right)\)

∴ \(V_{02}-6=\frac{12420Å \mathrm{eV}}{\mathrm{e}}\left(-\frac{1}{12000}\right) \frac{1}Å; \quad V_{02}=\frac{-12420}{12000}+6=4.965 \mathrm{~V} \simeq 5 \mathrm{~V}\)

Question 10. Write three characteristic features in the photoelectric effect which cannot be explained based on the wave theory of light, but can be explained only using Einstein’s equation.

Answer:

  1. The instantaneous ejection of photoelectrons.
  2. Existence of threshold freq. for a metal surface.
  3. The fact that the K.E. of the emitted electrons is independent of the intensity of the light depends on its frequency.

Question 11. Plot a graph showing the variation of photoelectric current with intensity of light. The work function for the following metals is given:

Na: 2.75 eV and Mo: 4.17 eV

Which of these will not give photoelectron emission from a radiation of wavelength 3300 Å from a laser beam? What happens if the source of the laser beam is brought closer?

Answer:

Dual Nature Of Radiation And Matter Variation Of Photo Current With Intensity Of Light

For, \(\lambda=3300Å . E=\frac{h c}{\lambda}=\frac{6.6 \times 10^{-34} \times 3 \times 10^8}{3300 \times 10^{-10}}=6 \times 10^{-19} \mathrm{~J}=\frac{6 \times 10^{-19}}{1.6 \times 10^{-19}} \mathrm{eV}=3.75 \mathrm{eV}\)

Incident energy 3.75 eV <4.17 eV, so the photoelectric effect will not take place in Mo (4. 17 eV). Photocurrent will increase in Na if the source of the laser beam is brought closer.

Question 11. State two important properties of photons which are used to write Einstein’s photoelectric equation. Define

  1. Stopping potential and
  2. Threshold frequency, using Einstein’s equation and drawing necessary plots between relevant quantities.

Answer:

  1. The energy of a photon is proportional to the freq. of light. (E = hv)
  2. Photons are quanta or discrete carriers of energy.

Stopping potential: In the experiment of the photoelectric effect, the value of the negative potential of the anode at which photoelectric current reduces to zero is called slopping potential for the given freq. of incident radiation.

Threshold freq.: For a given material, there exists a certain min. frequency below which no photoelectron can come out from the metal surface. This is called threshold frequency.

Dual Nature Of Radiation And Matter Threshold Frequency

Question 12. Sketch the graphs showing the variation of stopping potential with the frequency of incident radiations for two photosensitive materials A and B having threshold frequencies vA > vB.

  1. In which case is the slopping potential more and why?
  2. Does the slope of the graph depend on the nature of the material used? Explain.

Answer:

Dual Nature Of Radiation And Matter Variation Of Stoping Potential

From eV0 = Kmax = hv – Φ

eV0 = hv- hv0

∴ \(V_0=\frac{h v}{e}-\frac{h v_0}{e}\)

1. From the above equation, we can conclude, that the more threshold freq., the less would be the slopping potential (V0). Here, v0A > v0B, hence slopping potential (V0) is greater for B than A.

2. \(V_0=\left(\frac{h}{c}\right) v-\frac{h}{c} v_0(y=m x \pm c)\)

The slope of the above equation is \(\left(\frac{\mathrm{h}}{\mathrm{c}}\right)\) which is ‘independent’ of the nature of the material.

Question 13. Using a photon picture of light, show how Einstein’s photoelectric equation can be established. Write two features of the photoelectric effect which cannot be explained by wave theory.

Answer:

Einstein states that electromagnetic radiation energy is built up of discrete units called quanta of energy and has energy hv where ‘h’ is Planck’s constant and ‘V’ is the frequency of light.

In this phenomenon, an e absorbs a quantum of energy (hv), if the energy absorbed exceeds the minimum energy needed to escape from metal (Φ0 ), e is emitted with maximum K.E.

∴ \(\mathrm{K}_{\text {max }}=h v-\phi_0\) [Einstein’s photo electric equation]

Two features of PEE which can’t be explained by wave theory

  1. A min. frequency (threshold frequency) exists for diff. metals below which PEE is not possible.
  2. PEE is an instantaneous phenomenon.

Question 14. Define the term ‘cut-off frequency” in photoelectric emission. The threshold frequency of a metal is f. When the light of frequency 2f is incident on the metal plate, the maximum velocity of photo-electrons is V1. When the frequency of the incident radiation is increased to 5f, the maximum velocity of photo-electrons is v2. Find the ratio: v1: v2.

Answer:

Cut-off Frequency: The minimum. frcq. of incident light which can emit photoelectrons from a material is known as cut-off frequency.

From eq. KEmax = hv- hv0

⇒ \(\frac{1}{2} m v_1^2=h(2f)-hf=hf\) → (1)

⇒ \(\frac{1}{2} m v_2^2=h(5f)-hf=4 hf\) → (2)

∴ \(\frac{v_1^2}{v_2^2}=\frac{1}{4} \Rightarrow \frac{v_1}{v_2}=\frac{1}{2} \Rightarrow v_1: v_2=1: 2\)

Question 15. The given graph shows the variation of photo-electric current (I) with the applied voltage (V) for two different materials and for two different intensities of the incident radiation. Identify and explain using, Einstein’s photoelectric equation the pair of curves that correspond to

  1. Different materials but the same intensity of incident radiation,
  2. Different intensities but the same materials.

Dual Nature Of Radiation And Matter Variation Of Photo Electric Current

Answer:

  1. (1,2) and (3,4) are diff. materials of the same intensity. The saturation current is the same but the stopping potential is different.
  2. ( 1,3) and (2,4) have diff. intensities but the same materials. As saturation currents arc differently slopping potential is the same.

Question 16.

  1. Calculate the frequency of a photon of energy 6.5 x 10-19 J.
  2. Can this photon cause the emission of an electron from the surface of Cs of work function 2.14 eV? If yes, what will be the maximum kinetic energy of the photoelectron?

Answer:

1. Energy E=hv

∴ \(v=\frac{E}{h}=\frac{6.5 \times 10^{-19}}{6.63 \times 10^{-34}}=0.98 \times 10^{15}=9.8 \times 10^{14} \mathrm{Hz}\)

2. Work function Φ0 = 2.14 eV

The energy of photons in eV

∴ \(E=\frac{6.5 \times 10^{-19}}{1.6 \times 10^{19}}=4.06 \mathrm{eV}\)

KEmax = E – Φ0 = 4.06 – 2.1 4 = 1 .92 eV

CBSE Class 12 Physics Chapter 11  Dual Nature Of Radiation And Matter Long Questions And Answers

Question 1. The photoelectric emission is possible only if the incident light is in the form of packets of energy, each having a definite value, more than the work function of the metal. This shows that light is not of wave nature but of particle nature. It is for this reason that photoelectric emission was accounted for by the quantum theory of light.

(1). Packets of energy are called

  1. Electron
  2. Quanta
  3. Frequency
  4. Neutron

Answer: 2. Quanta

(2). Energy associated with each photon

  1. hc
  2. mc
  3. hv
  4. hk

Answer: 3. hv

(3). Which of the following waves can produce the photoelectric effect

  1. UV radiation
  2. Infrared radiation
  3. Radio waves
  4. Microwaves

Answer: 1. UV radiation

(4). The work function of alkali metals is

  1. Less than zero
  2. Just equal to other metals
  3. Greater than other metals
  4. Quite less than other metals

Answer: 4. Quite less than other metals

Question 2. According to de-Broglie a moving material particle sometimes acts as a wave and sometimes as a particle or a wave is associated with a moving material particle which controls the particle in every respect. The wave associated with moving material particles is called matter wave or de-Broglie wave whose wavelength called dc-Broglic wavelength, is given by λ = h/mv.

(1). The dual nature of light is exhibited by

  1. Diffraction and photoelectric effect
  2. Photoelectric effect
  3. Refraction and interference
  4. Diffraction and reflection.

Answer: 1. Diffraction and photoelectric effect

(2). If the momentum of a particle is doubled, then its de-Broglie wavelength will:

  1. Remain unchanged
  2. Become four times
  3. Become two times
  4. Become half

Answer: 4. Become half

(3). If an electron and proton are propagating in the form of waves having the same X, it implies that they have the same:

  1. Energy
  2. Momentum
  3. Velocity
  4. Angular momentum

Answer: 2. Momentum

(4). Velocity of a body of mass m, having de-Broglie wavelength λ, is given by the relation:

  1. v = λ h/m
  2. v = λ m/h
  3. v = λ/hm
  4. v = h/λm

Answer: 4. v = h/λm

Important Questions for CBSE Class 12 Physics Chapter 10 Wave Optics

 CBSE Class 12 Physics Chapter 10 Wave Optics Multiple Choice Questions And Answers

Important Questions for CBSE Class 12 Physics Chapter 10 Wave Optics

Question 1. The distance between two slits in Young’s experiment is 0.2 mm. If the wavelength of the light used is 5000 Å, the angular position of the 5th dark fringe from the central bright fringe is _________ rad.

  1. 0.11
  2. 1.1
  3. 0.012
  4. 0.0011

Answer: 3. 0.11

Read and Learn More Important Questions for Class 12 Physics with Answers

⇒ \(y_n=\frac{5 \lambda D}{d}\)

Angular position,

⇒ \(\theta_n=\frac{n \lambda}{d}\)

∴ \(\theta_5=\frac{5 \lambda}{d}=\frac{5 \times 5000 \times 10^{-10}}{0.2 \times 10^{-3}}\)

Question 2. The angular spread of the central maximum, in the diffraction pattern, does not depend on _________.

  1. The Distance between the slit and the sources
  2. Wavelength of light
  3. Width of slit
  4. Frequency of light

Answer: 1. The Distance between the slit and the sources

Question 3. In Young’s double-slit experiment, the width of the source slit is increased then _______.

  1. The fringe pattern gets sharper and sharper
  2. Instead of interference, diffraction appears
  3. The angular distance between fringes increased
  4. Fringe pattern gels less and less sharp

Answer: 4. Fringe pattern gels less and less sharp

Question 4. In a two-slit experiment, the screen is placed one meter away. When light of wavelength 500 nm is used the fringe separation is 0.5 mm. The distance between two slits is ________ mm.

  1. 2
  2. 5
  3. 1
  4. 4

Answer: 3. 1

⇒ \(\beta=\frac{\lambda \mathrm{D}}{\mathrm{d}}\)

⇒ \(\mathrm{d}=\frac{\lambda \mathrm{D}}{\beta}=\frac{500 \times 10^-9 \times 1}{0.5 \times 10^{-3}}\)

∴ d = 10-3 m = 1nm

Question 5. If the phase difference between two waves is 6π radian, then the corresponding path difference is _________.

  1. λ

Answer: 4. 3λ

⇒ \(\frac{\Delta x}{\lambda}=\frac{\phi}{2 \pi}\)

⇒ \(\Delta x=\frac{6 \pi}{2 \pi} \times \lambda\)

∴ Δx = 3λ

Question 6. The intensity of a result wave obtained by the superposition of two waves is _______ amplitude of the resultant wave.

  1. Directly proportional to the cube of
  2. Directly proportional to
  3. Directly proportional to the square of
  4. Directly proportional to the square root of

Answer: 3. Directly proportional to the square of

 CBSE Class 12 Physics Chapter 10 Wave Optics Assertion And Reason

For question numbers 1 to 5, two statements are given: Assertion (A) and Reason (R). Select the correct answer to these questions from the codes (1), (2), (3) and (4) as given below.

  1. Both A and R are true and R is the correct explanation of A
  2. Both A and R are true but R is NOT the correct explanation of A
  3. A is true but R is false
  4. A is false and R is also false

Question 1. Assertion: If white light is used in YDSE, the central bright fringe will be white.

Reason: Because all the wavelengths produce their zero-order maxima at the same position.

Answer: 1. Both A and R are true and R is the correct explanation of A

Question 2. Assertion: Diffraction of sound waves is more easily observed than light waves.

Reason: Wavelength of sound waves is more as compared to light.

Answer: 1. Both A and R are true and R is the correct explanation of A

Question 3. Assertion: In interference light energy is redistributed.

Reason: There is no gain or loss of energy, which is consistent with the principle of energy conservation.

Answer: 1. Both A and R are true and R is the correct explanation of A

Question 4. Assertion: No interference pattern is detected when two coherent sources are infinitely close to each other.

Reason: The fringe width is inversely proportional to the distance between the two slits.

Answer: 1. Both A and R are true and R is the correct explanation of A

Question 5. Assertion: In Young’s experiment, the fringe width for dark fringes is different from that for white fringes.

Reason: In Young’s double slit experiment the fringes arc formed with a source of white light then only black and bright fringes are observed.

Answer: 4. A is false and R is also false

 CBSE Class 12 Physics Chapter 10 Wave Optics Short Questions And Answers

Question 1. Explain the formation of the fringes due to diffraction at a single slit, when the path difference of light waves from the ends of the slit on reaching a point on the screen is

  1. λ
  2. \(\frac{3 \lambda}{2}\)

Answer:

  1. When the path difference is λ. then we get the first minima on screen.
  2. When the Path difference is \(\frac{3 \lambda}{2}\) then we get the first secondary maxima on screen.

Question 2. How would the angular width of the central maximum of diffraction pattern be affected when

  1. The width of the slit is decreased, and
  2. Monochromatic light is replaced by polychromatic light. Justify your answers.

Answer:

In diffraction

⇒ \(\theta=\frac{2 \lambda}{d}\)

  1. Angular width will increase \(\theta \propto \frac{1}{d}\)
  2. The diffracted image gets dispersed into constituent colours of white light.

Question 3. Compare the interference pattern observed in Young’s double-slit experiment with the single-slit diffraction pattern, pointing out three distinguishing features.

Answer:

Wave Optics Young's Double Slit Experiment

Question 4. Define the term wavefront. State Huygen’s principle. Consider a plane wave front incident on a thin convex lens. Draw a proper diagram to show how the incident wave from transverse through the lens and after refraction focuses on the focal point of the lens, giving the shape of the emergent wavefront.

Answer:

Wavefront: The Locus of all the points vibrating in the same phase is called wavefront.

Huygens Principle states that every point on a wavefront is a source of new disturbance which travels further in the form of secondary wavelets. These wavelets spread out in the forward direction at the same speed as the source wave. A new wavefront is a tangential surface to the secondary wavelets.

Wave Optics Huygen's Principle

Question 5.

  1. Derive Snell’s law on the basis of Huygens wave Ihcory when light is travelling from a denser to a rarer medium.
  2. Draw the sketches to differentiate between plane wavefront and spherical wavefront.

Answer:

Wave Optics Snell's Law

Proof of SNELL’S Law:

Consider a plane wavefront (AB) incident on the surface XY. separating two media. Let the secondary wavelets from point (B) reach up to point (C) in lime (t). So draw an arc of length (v2t) from point A to locate the position of refracted WF. Now we draw a tangent (CD) on this arc where CD represents refracted WF.

Incident ray, refracted ray & the normal arc respectively1 to incident WF. refracted WF and surface XY.

Also, \(\sin \mathrm{i}=\frac{\mathrm{BC}}{\mathrm{AC}}=\frac{v_1 t}{A C}\) → (1)

and \(\sin r=\frac{A D}{A C}=\frac{v_2 t}{A C}\) → (2)

From (1) and (2)

∴ \(\frac{v_1}{v_2}=\frac{\sin i}{\sin r}\)

Or \(\frac{\mu_2}{\mu_1}=\frac{\sin i}{\sin r}\)

Hence Snell’s law is proved

Wave Optics Plane Wavefront And Spherical Wavefront

Question 6.

  1. In Young’s double slit experiment, two slits arc I mm apart and the screen is placed 1 m away from the slits. Calculate the fringe width when light of wavelength 500 nm is used.
  2. What should be the width of each slit to obtain 10 maxima of the double slit pattern within the central maximum of the single slit pattern?

Answer:

d = 1 mm, D = I m, λ = 500 nm (given)

∴ \(\beta=\frac{\lambda \mathrm{D}}{\mathrm{d}}=\frac{500 \times 10^{-9} \times 1}{10^{-3}} \mathrm{~m}=500 \times 10^{-6} \mathrm{~m}=500 \mu \mathrm{m}\)

2. In single slit diffraction, path diff. = a sinθ ≅ aθ = X ⇒ θ = λ/a

Width of central maxima of single slit = 2λ/a

Width of 10 maxima = 10 x fringe spacing = 10 x λ/6

Width of central maximum of single slit = Width of 10 maxima of double slit

∴ \(\frac{10 \lambda}{d}=\frac{2 \lambda}{a} \Rightarrow a=\frac{d}{5}=0.2 \mathrm{~mm}\)

Question 7. Two harmonic waves of monochromatic light y1 = a cos ωt and y2 = a cos(ωt +Φ) are superimposed on each other. Show that the maximum intensity in the interference pattern is four times the intensity due to each slit. Hence write the conditions for constructive and destructive interference in terms of the phase angle Φ.

Answer:

Given, y, = a cos ωt, y, = a cos(ωt + Φ)

Resultant displacement is given as:

y = y1 +y2

= a cos ωt + a cos(ωt + Φ)

= a cos ωt + a cos ωt cos Φ – a sin ωt sin Φ

= a cos ωt (1+ cos Φ)- a sin ωt sin Φ

Put R cos θ = a (1 + cos Φ) → (1)

R sin θ = a sin Φ → (2)

By squaring and adding Eqs. (1) and (2), we get

R2 = a2(1+cos + 2cosΦ) + a2sin– 2a2( 1 + cos Φ ) = 4a2cos2Φ/2

∴ \(I=R^2=4 a^2 \cos ^2 \frac{\phi}{2}=4 I_0 \cos ^2 \frac{\phi}{2}\)

1. For constructive interference,

∴ \(\cos \frac{\phi}{2}= \pm 1 \text { or } \frac{\phi}{2}=n \pi \text { or } \phi=2 n \pi, n=0,1,2 \ldots\)

2. For destructive interference,

∴ \(\cos \frac{\phi}{2}=0 \text { or } \frac{\phi}{2}=(2 n+1) \frac{\pi}{2} \text { or } \phi=(2 n+1) \pi, n=0,1,2 \ldots\)

Question 8.

  1. If one of two identical slits producing interference in Young’s experiment is covered with glass, so that the light intensity passing through it is reduced to 50%, find the ratio of the maximum and minimum intensity of the fringe in the interference pattern.
  2. What kind of fringes do you expect to observe if white light is used instead of monochromatic light?

Answer:

1. Let the intensity through one of the slits be I1 =1.

So. intensity of light through the slit covered by glass

I2 = 0.5I

Maximum intensity \(I_{\max }=\left(\sqrt{I_1}+\sqrt{I_2}\right)^2\)

⇒ \(I_{\mathrm{max}}=(\sqrt{\mathrm{I}}+\sqrt{0.5 \mathrm{I}})^2=2.9 \mathrm{I}\)

Minimum Intensity = \(I_{\min }=\left(\sqrt{I_1}-\sqrt{I_2}\right)^2\)

⇒ \(I_{\min }=(\sqrt{I}-\sqrt{0.5 I})^2=0.086 I\)

Thus ratio of intensities \(\frac{I_{\max }}{I_{\min }}=\frac{2.9}{0.086}=33.8\)

2. If white light is used in place of monochromatic light, then the central fringe will be white and some coloured fringes will be seen adjacent to the central fringe.

Question 9. Explain the following, giving reasons:

  1. When monochromatic light is incident on a surface separating two media, the reflected and refracted light both have the same frequency as the incident frequency.
  2. When light travels from a rarer to a denser medium, the speed decreases, does this decrease in speed imply a reduction in the energy carried by the wave?
  3. In the wave picture of light, the intensity of light is determined by the square of the amplitude of the wave. What determines the intensity in the photon picture of light?

Answer:

  1. Reflection and refraction arise through the interaction of incident light with the atomic constituents of matter. Atoms may be viewed as oscillators, which light up the frequency of the external agency (light) causing forced oscillations. The frequency of emitted light by a charged oscillator equals to its freq. of oscillation. Thus, the frequency of scattered light equals the frequency of incident light.
  2. No, the energy carried by a wave depends on the amplitude of the wave, not on the speed of
    wave.
  3. For a given frequency, the intensity of light in the photon picture is determined by the no. of photons lulling on unit area per unit time.

Question 10. Monochromatic light of wavelength 600 nm is incident from air on a water surface. The refractive index of water is 1.33. Find the

  1. Wavelength,
  2. Frequency and
  3. Speed, of reflected and refracted light.

Answer:

Given: X = 600 nm, \(\mathrm{n}_{\mathrm{w}}=\frac{4}{3}=1.33\)

Wave Optics Monochromatic Light

Frequency of incident ray

⇒ \(c=f \lambda \Rightarrow f=\frac{c}{\lambda}=\frac{3 \times 10^8}{600 \times 10^{-10}}\)

f = 5 x 1014 Hz

Wave Optics Frequency Of Incident Ray

Question 11.

  1. Stale two conditions for two light sources to be coherent.
  2. Give two points of difference between an interference pattern due to a double-slit and a diffraction pattern due to a single slit.

Answer:

  1. Two sources are said to be coherent if-
    • These produce waves of the same frequency with
    • Constant or zero phase difference
  2. Interference is the result of the superposition of secondary wavelets from two different slits while diffraction results due to the superposition of secondary wavelets from different parts of the same source slit.
    • In the interference pattern, all maxima are equally bright while in the case of diffraction, maxima are of decreasing intensity.

Question 12. How is the spacing between fringes in a double slit experiment affected if:

  1. The slits separation is increased.
  2. The colour of light used is changed from red to blue.
  3. The whole apparatus is submerged in an oil with a refractive index of 1.2.

Justify your answer in each case

Answer:

Spacing between fringes in a double slit experiment is given by \(\beta=\frac{\lambda \mathrm{D}}{\mathrm{d}}\)

Where, λ => Wavelength of light; d ⇒ Slit separation; D ⇒ Distance between slit and screen

On increasing *d’ fringe width decreases

λred > λblue. So ‘β’ decreases.

When the whole apparatus is immersed in oil of refractive index 1 .2. the wavelength decreases.

∴ \(\lambda^{\prime}=\frac{\lambda}{1.2}\)

∴ \(\beta^{\prime}=\frac{\lambda^{\prime} \mathrm{D}}{\mathrm{d}}\)= \(\beta^{\prime}=\frac{\beta}{1.2}\)

It means fringe width decreases.

 CBSE Class 12 Physics Chapter 10 Wave Optics Long Questions and Answers

Question 1. Wavefront is a locus of points which vibrates in the same phase. A ray of light is perpendicular to the wavefront. According to Huygens principle, each point of the wavefront is the source of a secondary disturbance and the wavelets connecting from these points spread out in all directions with the speed of the wave. The figure shows a surface XY separating two transparent media. medium- 1 and medium-2. The lines ah and cd represent wavefronts of a light wave\e tra\elling in medium- 1 and incident on XY. The lines of and gh represent wavefronts of the light wa\c in medium -2 after refraction.

Wave Optics Wvavefront Is A Focus Length Of Point

(1). Light travels as a

  1. Parallel beam in each medium
  2. Convergent beam in each medium
  3. Divergent beam in each medium
  4. Divergent beam in one medium and convergent beam in the other medium

Answer: 1. Parallel beam in each medium

(2). The phases of the light wave at c, d, c and f are Φc, Φd, Φe, and Φf respectively. It is given that Φc = Φf

  1. Φc can not be equal to Φd
  2. Φd can be equal to Φe
  3. (Φd Φf) is equal to (ΦcΦe)
  4. (ΦdΦc ) is not equal to (Φf Φe)

Answer: 3. (Φd Φf) is equal to (ΦcΦe)

(3). Wavefront is the locus of all points, where the particles of the medium vibrate with the same

  1. Phase
  2. Amplitude
  3. Frequency
  4. Period

Answer: 1. Phase

(4). A point source that emits waves uniformly in all directions, produces wavefronts that are

  1. Spherical
  2. Elliptical
  3. Cylindrical
  4. Planar

Answer: 1. Spherical

Question 2.

  1. Define a wavefront. Using Huygens principle, verify the laws of reflection at a plane Surface
  2. In a single slit diffraction experiment, the width of the slit is made double the original width. How does this affect the size and intensity of the central diffraction band? Explain.
  3. When a tiny circular obstacle is placed in the path of light from a distant source, a bright spot is seen at the centre of the obstacle. Explain why?

Answer:

1. The wavefront is defined as a surface of constant phase.

(Alternatively: The wavefront is the locus of all points in the same phase).

Wave Optics Surface Of Constant Phase

Let the speed of the wave in the medium be ‘v’

Let the time taken by the wavefront, to advance from point B to point C is ‘τ’

Hence BC = vτ

Let CE represent the reflected wavefront. Distance AE = vτ = BC

Δ AEC and Δ ABC are congruent

∴ ∠ABC = ∠AEC(90°)

AC = AC

AE = BC.

So, ∠BAC = ∠ECA (by corresponding part of congruent triangles)

= ∠i = ∠r (proved)

2. If the width of the slit is made double then the size of the central maxima reduces to half and intensity increases upto four times.

3. This is because of the diffraction of light.

[Alternatively: Light gels diffracted by the tiny circular obstacle and reach the centre of the shadow of the obstacle.]

[Alternatively: There is a maxima, at the centre of the obstacle, in the diffraction pattern produced by it.]

Question 3.

  1. Give an expression for path difference in Young’s double slit experiment and obtain the conditions for constructive and destructive interference at a point on the screen.
  2. The intensity at the central maxima in Young’s double-slit experiment is I0. Find out the intensity at a point where the path difference is \(\frac{\lambda}{6},\frac{\lambda}{4} \text { and } \frac{\lambda}{3}\)

Answer:

1. Conditions for interference of light:

  • Both sources of light must be coherent.
  • Both sources of light should be monochromatic.

Expression for fringe width in Young’s double slit experiment:

Path difference between the light waves reaching point P from S1 and S2

Δx = S2P -S1P

Path difference \((\Delta \mathrm{x})=\frac{\mathrm{y}_{\mathrm{n}} \mathrm{d}}{\mathrm{D}}\)

Wave Optics Fringe Width Young's Double Slit Experiment

Case (1) Position of bright fringes:

If nth bright fringe occurs at point P. then the path difference

Δx = nλ

∴ \(\frac{y_n d}{D}=n \lambda \Rightarrow y_n=\frac{n \lambda D}{d} \text { where } n=0,1,2,3, \ldots .\)

yn ⇒ position of nth bright fringe on screen from the central bright fringe.

Case (2) Position of dark fringes:

Path difference for nth dark fringe

Δx = (2n – I )λ/2

⇒ \(\frac{y_n^{\prime} d}{D}=(2 n-1) \lambda/2\)

⇒ \(y_n^{\prime}=\frac{(2 n-1) \lambda D}{2 d} \text { where } n=1,2,3, \ldots .\)

y’n ⇒ position of nth dark fringe.

Fringe width:

The distance between two consecutive bright or dark fringes is called fringe width.

fringe width \((\beta)=y_{n+1}-y_n\) (Taking Condition for bright fringe \(y_n=\frac{n{\lambda}D}{\mathrm{d}}\))

⇒ \(\beta=\frac{(n+1)\lambda D}{d}-\frac{n \lambda D}{d}\)

∴ \(\beta=\frac{\lambda D}{d}\)

Intensity distribution curve:

Wave Optics Intensity Distribution Curve

2. As we Know, I = 4I0 Cos2(Φ/2)

Φ = Phase difference

⇒ \(\phi=\frac{2 \pi}{\lambda} \cdot \Delta x\) (Δx = path diff.)

(1) From, \(\phi=\frac{2 \pi}{\lambda} \cdot \Delta x=\frac{2 \pi}{\lambda} \cdot \frac{\lambda}{6}\)

Φ = π/3 = 60°

So, \(I=4 I_0 \cos ^2 30^{\circ}=4 I_0 \cdot \frac{3}{4}\)

I = 3I0

(2). From \(\phi=\frac{2 \pi}{\lambda} \cdot \Delta x=\frac{2 \pi}{\lambda} \cdot \frac{\lambda}{4}=\frac{\pi}{2}=90^{\circ}\)

So, \(I=4 I_0 \cos ^2 45^{\circ}=4 I_0 \cdot \frac{1}{2}\)

I = 2 I0

(3). From, \(\phi=\frac{2 \pi}{\lambda} \cdot \Delta x=\frac{2 \pi}{\lambda} \cdot \frac{\lambda}{3}=\frac{2 \pi}{3}=120^{\circ}\)

So, \(I=4 I_0 \cos ^2 60^{\circ}=4 I_0 \cdot \frac{1}{4}\)

I = I0

Question 4.

  1. State the essential conditions for diffraction of light.
  2. Explain the diffraction of light due to a narrow single slit and the formation of a pattern of fringes on the screen.
  3. Find the relation for the width of central maximum in terms of wavelength ‘λ’ width of slit ‘a’, and separation between slit and screen ‘D’.
  4. If the width of the slit is made double the original width, how does it affect the size and intensity of the central band?

Answer:

1. The wavelength of light should be comparable to the site of the obstacle,

2. Suppose a plane wavefront is incident on a slit AH (of width b), every part of the exposed part of the plane wavefront (i.e., every part of the slit) acts as a source of secondary wavelets spreading in all directions.

The diffraction is obtained on a screen placed at a large distance. (In practice, this condition is achieved by placing the screen at the focal plane of a converging lens placed to alter the slit).

Wave Optics Plane Wave Front Is Incident On A Slit

  • The diffraction pattern consists of a central bright fringe (central maxima) surrounded by dark and bright lines (called secondary minima and maxima).
  • At point 0 on the screen, the central maxima is obtained. The wavelets originating from points A and B meet in the same phase at this point, hence at 0, intensity is maximum.

Secondary minima

For obtaining nth secondary minima at P on the screen, the path difference between the diffracted waves Δ = b sinθ = nλ (n = 0,1, 2, … )

Angular position of nth secondary minima

⇒ \(\sin \theta \simeq 0=\frac{n {\lambda}}{b}\)

Distance of nth secondary minima from central maxima

⇒ \(x_n=D \cdot \theta=\frac{n \lambda D}{b}=\frac{n \lambda f}{b}\)

where D = distance between slit and screen.

f ≅ D = Focal length of converging lens.

Secondary maxima:

For nth secondary maxima at P on the screen.

Path difference. \(\Delta=b \sin \theta =(2 n+1) \frac{\lambda}{2}\); where n = 1,2,3….

Angular position of nth secondary maxima

∴ \(\sin \theta \simeq \theta=\frac{(2 n+1) \lambda}{2 b}\)

Distance of nth secondary maxima,from central maxima

∴ \(x_n=D \cdot \theta=\frac{(2 n+1) \lambda D}{2 b}=\frac{(2 n+1) \lambda f}{2 b}\)

Wave Optics Secondary Maxima

3. The Central Maximum:

The width of the central maximum is simply the distance between the 1st order minima from the centre of the screen on both sides of the centre.

The position of the minima given by ‘y’ (measured from the centre of the screen) is:

The position of the minima given by ‘y’ (measured from the centre of the screen) is:

∴ \(\tan \theta \simeq \theta=\frac{y}{D}\)

For small θ, sinθ ≅ θ

λ = bsinθ – bθ

⇒ \(\theta=\frac{y}{D}=\frac{\lambda}{b}\)

⇒ \(y=\frac{\lambda D}{b}\)

The width of the central maximum is simply twice this value width of central maximum = \(2 \frac{\lambda D}{b}\)

angular width of central maximum = 2θ = \(2 \frac{\lambda}{b}\)

4. If the width of the slit is made double then the size of the central maxima reduces to half and intensity increases upto four times.

Important Questions for CBSE Class 12 Physics Chapter 9 Ray Optics and Optical Instruments

 CBSE Class 12 Physics Chapter 9 Ray Optics And Optical Instruments Multiple Choice Questions And Answers

Important Questions for CBSE Class 12 Physics Chapter 9 Ray Optics and Optical Instruments

Question 1. For a thin convex lens when the height of the object is double its image, its object distance is equal to ________.

  1. f
  2. 2f
  3. 3f
  4. 4f

Answer: 3. 3f

⇒ \(m=\frac{f}{f-u}\)

⇒ \(-\frac{1}{2}=\frac{f}{f-(-u)}\)

⇒ -f-u = 2f

∴ |u| = 3f

Read and Learn More Important Questions for Class 12 Physics with Answers

Question 2. Which of the following is responsible for the glittering of diamonds?

  1. Interference
  2. Diffraction
  3. Total internal reflection
  4. Refraction

Answer: 3. Total internal reflection

Question 3. The focal length of a thin lens made from the material of a refractive index of 1.5 is 20 cm. When it is placed in a liquid of refractive index 4/3 its focal length will be _________ cm.

  1. 80.00
  2. 60.25
  3. 45.48
  4. 78.23

Answer: 4. 45.48

⇒ \(\frac{f_1}{f_a}=\left(\frac{_a \mu_g-1}{_l \mu_z-1}\right)\)

⇒ \(\frac{f_l}{20}=\frac{(1.5-1)}{\left(\begin{array}{l}
1.5 \\
1.33
\end{array}\right)}\)

∴ fl = 78.23 cm

Question 4. The radii of curvature of both sides of a convex lens are 15 cm and if the refractive index of the material of the lens is 1.5. Then the focal length of the lens in air is _________ cm.

  1. 10
  2. 15
  3. 20
  4. 30

Answer: 2. 15

⇒ \(\frac{1}{f_a}=\left(_a\mu_g-1\right)\left(\frac{1}{R_1}-\frac{1}{R_2}\right)\)

⇒ \(\frac{1}{f_a}=\frac{1}{2}\left(\frac{1}{15}-\frac{1}{-15}\right)\)

⇒ \(\frac{1}{f_a}=\frac{1}{2} \times \frac{2}{15}\)

∴ fa = 15 cm

Question 5. If the tube length of the astronomical telescope is 105 cm and the magnifying power is 20 for a normal setting, then the focal length of the objective is ________ cm.

  1. 10
  2. 20
  3. 25
  4. 100

Answer: 4. 100

Question 6. An object is placed at a distance of 25 cm on the axis of a concave mirror having a focal length of 20 cm. What will be the lateral magnification of an image?

  1. 4
  2. 2
  3. -4
  4. -2

Answer: 3. -4

⇒ \(m=\frac{f}{f-u}\)

⇒ \(\frac{-20}{-20-(-25)}=\frac{-20}{5}\)

∴ m = -4

Question 7. The depth of a filled well is II m and the refractive index of water is 1.33. If viewed normally from the top, by how much height would the bottom of the well appear to be shifted up?

  1. 2.73 m
  2. 11 m
  3. 4.13 m
  4. 1.37 m

Answer: 1. 2.73 m

⇒ \(h=\frac{H}{\mu}=\frac{11}{4} \times 3=\frac{33}{4}\)

Vertical shifted

⇒ \(H-h=11-\frac{33}{4}\)

∴ \(\frac{44-33}{4}=\frac{11}{4}=2.73 \mathrm{~m}\)

Question 8. In an optical fibre, the refractive index of the material of the core is _______ that of the cladding.

  1. Less than
  2. Higher than
  3. Equal to
  4. Half

Answer: 2. Higher than

Question 9. The lower half of the concave mirror’s reflecting surface is covered with an opaque (non – reflective) material. The intensity of the image of an object placed in front of the mirror becomes ________.

  1. Four times
  2. Half
  3. One fourth
  4. Double

Answer: 2. Half

Question 10. If the focal length of the converging lens is 0.25 m then the power of this lens is _____ dioptre.

  1. +2
  2. -4
  3. +4
  4. -2

Answer: 3. +4

∴ \(P=\frac{1}{f}=\frac{1}{0.25}=4 D\)

 CBSE Class 12 Physics Chapter 9 Assertion And Reason

For question numbers 1 to 6 two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (1), (2), (3) and (4) as given below.

  1. Both A and R are true and R is the correct explanation of A
  2. Both A and R are true but R is NOT the correct explanation of A
  3. A is true but R is false
  4. A is false and R is also false

Question 1. Assertion: Critical angle is minimum for violet colour.

Reason: Because critical angle \(\theta_c=\sin ^{-1}\left(\frac{1}{\mu}\right) \text { and } \mu \propto \frac{1}{\lambda} \)

Answer: 1. Both A and R are true and R is the correct explanation of A

Question 2. Assertion: Within a glass slab a double convex air bubble is formed. This air bubble behaves like a converging lens.

Reason: The refractive index of air is more than the refractive index of glass.

Answer: 4. A is false and R is also false

Question 3. Assertion: A beam of white light gives a spectrum on passing through a hollow prism.

Reason: The speed of light outside the prism is different from the speed of light inside the hollow prism.

Answer: 4. A is false and R is also false

Question 4. Assertion: The microscope magnifies the image.

Reason: Angular magnification for images is more than one in the microscope.

Answer: 1. Both A and R are true and R is the correct explanation of A

Question 5. Assertion: Spherical aberration occurs in lenses of larger aperture.

Reason: The two types of rays, paraxial and marginal rays focus at different points.

Answer: 1. Both A and R are true and R is the correct explanation of A

Question 6. Assertion: The angle of minimum deviation for a prism is lesser for red light than that for blue light.

Reason: The refractive index of the material of a prism for blue light is greater than that for red light.

Answer: 1. Both A and R are true and R is the correct explanation of A

 CBSE Class 12 Physics Chapter 9 Short Question And Answers

Question 1. Light from a point source in the air falls on a convex spherical glass surface with a refractive index of 1.5 and a radius of curvature of 20 cm. The distance of the light source from the glass surface is 100 cm. At what position is the image formed?

Answer:

Given: 1 = 1, 2 = 1.5, R = 20cm. u = -100 cm

Form \(\frac{\mu_2}{v}-\frac{\mu_1}{u}=\frac{\mu_2-\mu_1}{R} \Rightarrow \frac{1.5}{v}-\frac{1}{-100}=\frac{0.5}{20}\)

⇒ \(\frac{1.5}{v}=\frac{5}{200}-\frac{1}{100}=\frac{3}{200} \text { or } v=100 \mathrm{~cm}\)

Question 2. A beam of light converges at a point P. A lens is placed in the path of the beam at a distance of 25 cm from P. The final image is formed at infinity. Calculate the power of the lens.

Answer:

So, u = 25 cm, v = ∞

⇒ \(\mathrm{f}=-25 \mathrm{~cm}=-\frac{25}{100} \mathrm{~m}=-\frac{1}{4} \mathrm{~m}\)

∴ \(P=\frac{l}{f}=-4 D\)

Ray Optics And Optical Instruments A Beam Of Light

Question 3. A ray of light falls on a transparent sphere of μ = √3 at an angle of incidence 60° with the diameter AB of the sphere having centre C. The ray emerges from the sphere parallel to the line AB. Find the angle of emergence.

Ray Optics And Optical Instruments A Ray Of Light Falls On A Transparent Sphere

Answer:

⇒ \(\mu=\frac{\sin i}{\sin r_1}\)

⇒ \(\sqrt{3}=\frac{\sin 60^{\circ}}{\sin r_1}\)

⇒ \(\sin r_1=\frac{\sqrt{3}}{2} \times \frac{1}{\sqrt{3}}\)

r1 = 30°

i.e. r1 = r2 = 30° so, e = 60° [angle of emergence]

Ray Optics And Optical Instruments Angle Of Emergence

Question 4.

  1. Explain briefly how the focal length of a convex lens changes with an increase in the wavelength of incident light.
  2. Explain briefly how the focal length of a convex lens changes when it is immersed in water. The refractive index of the material of the lens is greater than that of water.

Answer:

1. From \(\mu=\frac{\mathrm{c}}{\mathrm{v}}=\frac{\mathrm{c}}{\mathrm{v \lambda}}\)

Here, refractive index \(\mu \propto \frac{1}{\lambda}\)

So, (.t of a lens increases with the decrease in wavelength of the incident light.

From \(\frac{1}{f}=(\mu-1)\left(\frac{1}{R_1}-\frac{1}{R_2}\right)\)

We can say focal length will increase with the increase in wavelength and vice versa.

2. From, \(\frac{1}{f}=\left(\frac{\mu_2}{\mu_1}-1\right)\left[\frac{1}{R_1}-\frac{1}{R_2}\right]\) 2 (lens) = 1.5, 1 (Water) = 1.33

⇒ \(\frac{1}{f}=\left(\frac{1.5}{1.33}-1\right)\left[\frac{1}{R_1}-\frac{1}{R_2}\right]\) When lens placed in water

Clearly \(\left(\frac{\mu_2}{\mu_1}\right)\) decreases which means focal length increases.

Question 5. A ray PQ incident normally on the refracting face BA is refracted in the prism BCA made of material of refractive index 1.5. Complete the path of the ray through the prism. From which face will the ray emerge?

Ray Optics And Optical Instruments A Prism

Answer:

Refractive index (μ) = 1.5 (given)

Ray PQ will go straight in ΔBAC as it falls normally on the surface BA. From the condition of TIR.

⇒ \(\sin \mathrm{i}_C=\frac{1}{\mu}=\frac{1}{1.5}=\frac{2}{3}=0.66\)

or ic = 42° (∵ sin 42° = 0.66)

⇒ \(\frac{\sin i}{\sin r}=\frac{\mu_2}{\mu_1}=\frac{2}{3}\)

Ray Optics And Optical Instruments The Emerge

or \(\frac{\sin 30^{\circ}}{\sin r}=\frac{2}{3}\)

or sin r = 0.75

or r = 48.5° (∵ sin 48.5° = 0.75)

So ray PQ will emerge from surface AC at an angle = 48.5°

Question 6. A beam of light converges at a point P. Draw ray diagrams to show where the beam will converge if

  1. A convex lens, and
  2. A concave lens is kept in the path of the beam.

Answer:

Ray Optics And Optical Instruments Convex And Concave Lens

Question 7. A coin is placed inside a denser medium. Why does it appear to be raised? Obtain an expression for the height through which the object appears to be raised in terms of the refractive index of the medium and real depth.

Answer:

Because of Refraction, it appears to be raised.

Ray Optics And Optical Instruments Rarer Denser

⇒ \(\Delta \mathrm{OMP} \rightarrow \sin i=\frac{\mathrm{MP}}{\mathrm{OM}}\)

⇒ \(\Delta \mathrm{XMP} \rightarrow \sin r=\frac{\mathrm{MP}}{\mathrm{XM}}\)

So, \(\text { So, }{ }_d \mu_r=\frac{\sin i}{\sin r}=\frac{X M}{O M}\)

If M and P are closer, then XM ≅ XP = h’ (Apparent depth), OM = OP = H (Actual Depthdepth)

⇒ \({ }_d \mu_r=\frac{h^{\prime}}{h}\)

⇒ \(\frac{1}{{ }_r \mu_d}=\frac{h^{\prime}}{h}\)

∴ \(h^{\prime}=\frac{h}{\mu}\) (\(\left[d \mu_r=\frac{1}{\mu_d}=\frac{1}{_r\mu_1}\right]\))

Thus the height (vertical shift) through which, the object appears to be raised

∴ \(\Delta=h-h^{\prime}=h\left(1-\frac{1}{\mu}\right)\)

Question 8. Under what conditions does the phenomenon of total internal reflection lake place? Draw a ray diagram showing how a ray of light deviates by 90° after passing through a right-angled isosceles prism.

Answer:

Conditions:

  1. The light must move from a denser to a rarer medium.
  2. The angle of incidence must be greater than the critical angle.

Ray Optics And Optical Instruments Critical Angle

Question 9. State, with the help of a ray diagram, the working principle of optical fibres. Write one important use of optical fibres.

Answer:

Working principle of optical fibres: Optical fibres are extensively used for transmitting audio and video signals in the form of light from one end to another based on multiple total internal reflections at the interface of inner and outer layers which are known as core and cladding.

Ray Optics And Optical Instruments Working Principle Of Optical Fibers

Use: Used in visual examination of Internal organs like the stomach and intestine by the endoscopy in medical Science

Question 10. Which two aberrations do objectives of refracting telescope suffer from? How are these overcome in reflecting telescopes?

Two Aberrations: Spherical aberration & chromatic aberration. Spherical aberration in mirrors is corrected by using parabolic mirrors and in lenses it is corrected by using a lens with a small aperture or one side plane.

Chromatic aberration is reduced by using an achromatic combination of lenses in which materials with differing dispersive properties arc assembled to form a compound lens.

Question 11. A compound microscope consists of an objective lens of focal length 2 cm and an eyepiece of focal length 6.25 cm separated by a distance of 15 cm. How far from the objective should an object be placed to obtain the final image at the least distance of distinct vision (25 cm)? Calculate the magnifying power of the microscope.

Answer:

f0 = 2cm. fe = 6.25 cm. d = 15 cm. D = 25 cm. ve = -25 cm

⇒ \(\frac{1}{f_e}=\frac{1}{v_e}-\frac{1}{u_e} \Rightarrow \frac{1}{6.25}=\frac{1}{-25}-\frac{1}{u_e} \Rightarrow u_e=-5 \mathrm{~cm}\)

So. the image distance for the objective lens

v1 = d – ue = 15 – 5 = 10cm

Now again

⇒ \(\frac{1}{f_0}=\frac{1}{v_0}-\frac{1}{u_0} \Rightarrow \frac{1}{2}=\frac{1}{10}-\frac{1}{u_0} \Rightarrow u_0=-2.5 \mathrm{~cm}\)

Magnifying Power

⇒ \(m=\frac{-v_0}{u_0}\left(1+\frac{D}{f_c}\right)=\frac{10}{2.5}\left(1+\frac{25}{6.25}\right)\)

m = 20

Question 12.

  1. An object approaches a converging lens with a uniform speed of 5 m/s and slops at the focus. How- will the image move for the lens? Specify its nature.
  2. In a simple microscope, a convex lens of focal length 5 cm is used. Calculate the magnifying power when the object is placed at the focus of the lens.
  3. What is the power of a biconvex lens of refractive index n2 dipped in a liquid of refractive index n1? where n1 < n2?

Answer:

1. Moves away from the lens with a non-uniform speed.

For example: If f = 20 m,

u = -50m. -45m, -40m. -34m

v = 33.3m, 36m. 40m, 46.7m [by using lens formula]

2. \(m=\frac{D}{f}=\frac{25}{5}=5\)

Ray Optics And Optical Instruments Equiconvex lens

The lens behaves as a convex lens

⇒ \(\mathrm{P}=\frac{1}{\mathrm{f}}=\left(_1\mathrm{n}_2-1\right)\left(\frac{1}{\mathrm{R_1}}-\frac{1}{\mathrm{R}_2}\right)\)

⇒ \(P=\left(\frac{n_2}{n_1}-1\right)\left(\frac{1}{R_1}-\frac{1}{R_2}\right)\)

1n2 < an2 (∵ n1 can not be less than 1 )

So. Focal length will increase. power will decrease.

Question 13. Draw a labelled ray diagram of a refracting telescope. Deduce an expression of magnifying power of it. Write two main limitations of a refracting-type telescope or a reflecting-type telescope.

Answer:

Refracting Telescope:

Ray Optics And Optical Instruments Refracting Telescope

Refracting type telescope consists of an objective lens of large aperture and large focal length whereas an eyepiece is of small aperture and small focal length.

Magnifying Power:

It is the ratio of visual angle substandard by the final image at the eye to the visual angle subtended by an object.

⇒ \(M=\frac{\beta}{\alpha} \quad\left\{\begin{array}{l}
\text { if } \alpha \text { and } \beta \text { are very small } \\
\alpha \approx \tan \alpha \text { and } \beta \approx \tan \beta
\end{array}\right.\)

⇒ \(M=\frac{\tan \beta}{{tan} \alpha} \Rightarrow M=\frac{\left(\frac{A^{\prime} B^{\prime}}{O_2 B^{\prime}}\right)}{\left(\frac{A^{\prime} B^{\prime}}{O_1 B^{\prime}}\right)} ⇒ M=\frac{O_1 B^{\prime}}{O_2 B^{\prime}}=\frac{-f_0}{u_e}\)

⇒ \(M=\frac{-f_0}{u_e}\) (1)

1. When the final image is formed at least a distance of distinct Vision (Ve = D)

Applying lens formula for eyepiece:

⇒ \(\frac{1}{f_e}=\frac{1}{v_e}-\frac{1}{u_e} \quad\left\{\begin{array}{l}
\text { applying sign convention } \\
v_e=-D . \quad u_e=-u_e
\end{array}\right.\)

⇒ \(\frac{1}{f_e}=-\frac{1}{D}+\frac{1}{u_e} \Rightarrow \frac{1}{u_e}=\frac{1}{f_e}+\frac{1}{D} \Rightarrow \frac{f_0}{u_e}=f_0\left(\frac{1}{f_e}+\frac{1}{D}\right) \Rightarrow \frac{f_0}{u_e}=\frac{f_0}{f_e}\left(1+\frac{f_e}{D}\right)\)

Hence magnifying power from eq (1)

∴ \(M=-f_0\left[\frac{1}{f_e}+\frac{1}{D}\right]\)

2. When the final image is formed at infinity (ue = fe )

From eq. (i)

∴ \(M=\frac{-\mathrm{f}_0}{\mathrm{f}_e}\)

Drawbacks of refracting telescope:

  1. A defect of chromatic aberration occurs in refracting-type telescopes.
  2. It has a small resolving power

Question 14.

  1. Draw a ray diagram depicting the formation of the image by an astronomical telescope in normal adjustment.
  2. You are given the following three lenses. Which two lenses will you use as an eyepiece and as an objective to construct an astronomical telescope? give reason.

Ray Optics And Optical Instruments Astronomical telescope.

Answer:

Ray Optics And Optical Instruments Astronomical Telescope...

2. ‘L1‘ is used for an objective as it has the largest focal length which is needed, \(M_0=\frac{f_0}{f_e}\) for better-magnifying power. ‘L3‘ is Used for an eyepiece to get better angular magnification, as from \(M_{0}=\frac{f_{0}}{f_e}\) least fe is needed.

Question 15.

  1. A convex lens of focal length 30 cm is in contact with a concave lens of focal length 20 cm. Find out if the system is converging or diverging.
  2. Obtain the expression for the angle of incidence of a ray of light, which is incident on the face of a prism of refracting angle A so that it suffers total internal reflection at the other face. (Given, the refractive index of the glass of the prism is μ.)

Answer:

1. Focal length of convex lens f1 = 30 cm

the focal length of the concave lens f2 = -20 cm

Equivalent focal length of combination

⇒ \(\frac{1}{f}=\frac{1}{f_1}+\frac{1}{f_2} \Rightarrow \frac{1}{f}=\frac{1}{30}-\frac{1}{20} \Rightarrow \frac{1}{f}=-\frac{1}{60} \Rightarrow f =-60 \mathrm{~cm}\)

The system is diverging.

2. For total internal reflection.

⇒ \(\sin i_c=\frac{1}{\mu}\)

For Prism we know that

r1 + r2 = A and r2 = ic

∴ r1 = A -ic

Applying Snell’s law at point ‘Q’

∴ \(\frac{\sin i}{\sin f_i}=\mu\)

sin i = μ sin r1 ⇒ sin i = μ sin (A- ic)

i = sin-1 |μ sin-(A-ic)|

Ray Optics And Optical Instruments Angle Of Incidence Of A Ray Of Light

Question 16.

  1. Name the phenomenon on which the working of an optical fibre is based.
  2. Draw a labelled diagram of an optical fibre and show how light propagates through the optical fibre using this phenomenon.

Answer:

1. Total internal reflection (TIR)

Ray Optics And Optical Instruments Optical Fiber

Question 17.

  1. A screen is placed at a distance of 100 cm from an object. The image of the object is formed on the screen by a convex lens for two different locations of the lens separated by 20 cm. Calculate the focal length of the lens used.
  2. A converging lens is kept coaxially in contact with a diverging lens with equal focal length. What is the focal length of the combination?

Answer:

1. For the first position of the lens, we have

∴ \(\frac{1}{f}=\frac{1}{y}-\frac{1}{(-x)}\) → (1)

Ray Optics And Optical Instruments Convex Lens

For the second position of the lens, we have (2)

⇒ \(\frac{1}{f}=\frac{1}{y-20}-\frac{1}{[-(x+20)]}\) →(2)

From (1) and (2)

⇒ \(\frac{1}{y}+\frac{1}{x}=\frac{1}{(y-20)}+\frac{1}{(x+20)} \Rightarrow \frac{x+y}{x y}=\frac{(x+20)+(y-20)}{(y-20)(x+20)}\)

∴ xy = (y – 20) (x + 20) = xy – 20 x + 20 y- 400

∴ x – y = -20

Also, x + y = 100

x= 40 cm and y = 60 cm

∴ \(\frac{1}{f}=\frac{1}{60}-\frac{1}{-40}=\frac{2+3}{120}=\frac{5}{120}\)

∴ f = 24 cm

or

Distance between the image (screen) and the object, D = 100 cm.

Distance between two locations of the convex lens, d = 20cm

Focal length (f) = \(=\frac{D^2-d^2}{4 D}=\frac{(100)^2-(20)^2}{4 \times 100}\)

f = 24 cm.

2. \(\frac{1}{f}=\frac{1}{f_1}+\frac{1}{\left(-f_2\right)}=\frac{1}{f_1}-\frac{1}{f_2}\)

⇒ [/altex]\frac{1}{f}=\frac{f_2-f_1}{f2 f_1}[/latex]

∴ \(f=\frac{f_2 f_1}{f_2-f_1}\)

Ray Optics And Optical Instruments Focal Length Of The Combination

Question 18.

  1. Monochromatic light of wavelength 589 nm is incident from air on a water surface. If μ for water is 1.33, find the refracted light’s wavelength, frequency and speed.
  2. A double convex lens is made of glass with a refractive index of 1.55, with both faces of the same radius of curvature. Find the radius of curvature required, if the focal length is 20 cm.

Answer:

1. \(\lambda_{\text {air }}=589 \mathrm{~nm}, \mu_{\text {water }}=1.33\) (Given)

For water, \(\lambda_{w a t e r}, \frac{\mu_n}{\mu_a}=\frac{\lambda_a}{\lambda_n} \Rightarrow \lambda_w=\frac{589}{1.33}\)

∴ w = 442.8nm

Frequency of light remains constant.

Velocity, \(v=\frac{c}{\mu}=\frac{3 \times 10^8}{1.33}=2.25 \times 10^8 \mathrm{~m} / \mathrm{s}\)

2. From \(\frac{1}{f}=\left(\mu_{21}-1\right)\left[\frac{1}{R_1}-\frac{1}{R_2}\right] \quad\left\{\begin{array}{l}
\text { Using sign Convention } \\
R_1=+R \quad \text { for equi convex lens } \\
R_2=-R
\end{array}\right.\)

⇒ \(\frac{1}{f}=(1.55-1)\left[\frac{1}{R}-\left(-\frac{1}{R}\right)\right]\)

∴ \(\frac{1}{r}=(.55)\left[\frac{2}{R}\right]=\frac{1.1}{R} \Rightarrow \frac{1}{20}=\frac{1.1}{R} \Rightarrow R=1.1 \times 20=22 \mathrm{~cm}\)

Question 19.

  1. A triangular prism with a refracting angle of 60° is made of a transparent material of refractive index 2/√3.
  2. A ray of light is incident normally on the face AB as shown in the figure. Trace the path of the ray as it passes through the prism and calculate the angle of emergence and angle of deviation.

Ray Optics And Optical Instruments A Triangular Prism

Answer:

Ray Optics And Optical Instruments Angle Of Emergence And Angle Of Deviation

Given: ∠A = 60°, ∠i = 0°

At M: \(\sin \mathrm{i}_{\mathrm{C}}=\frac{1}{\mu}=\frac{\sqrt{3}}{2}=\sin 60^{\circ}\)

∴ ic = 60°

So the ray PQ after refraction from the face AC grazes along AC.

∴ ∠e = 90°

From ∠i = ∠e = ∠A + ∠δ

or 0° + 90° = 60° + ∠δ

∴ δ = 90° – 60° = 30°

Question 20.

  1. What is total internal reflection? Under what conditions does it occur?
  2. Find a relation between critical angle and refractive index.
  3. Name one phenomenon which is based on total internal reflection

Answer:

The complete reflection of a light ray at the boundary of two media, when the ray is going from a denser to a rarer medium is called TIR.

Condition:

  1. Light rays must pass from a denser to a rarer medium
  2. the angle of incidence must be greater than the critical angle, (i > ic).

Ray Optics And Optical Instruments Critical Angle And Refractive Index

In the above Ray Ao goes from denser (say water) to rarer (say air) medium, So using Snell’s law, \(\frac{\sin i}{\sin r}=\frac{\mu_2}{\mu_1}\)

or \(\frac{\sin i_c}{\sin 90^{\circ}}=\frac{\mu_2}{\mu_1}\) [Here, angle of incidence = ic and angle of refraction = 90°]

If refractive index of rarer medium = 1 (i.e. 2 = 1)

or \(\sin i_c=\frac{1}{\mu_1}=\frac{1}{\mu}\) = (∵ \(\))

3. Mirage or Brilliance of diamond.

Question 21. In the following diagram, an object ‘O’ is placed 15 cm in front of a convex lens L1 of focal length 20 cm and the final image is formed at ‘I’ at a distance of 80 cm from the second lens L2. Find the focal length of the lens L2.

Ray Optics And Optical Instruments The Focal length Of The Lens

Answer:

Ray Optics And Optical Instruments The Focal length Of The Lens..

For Lens L1: \(\frac{1}{v_1}-\frac{1}{u_1}=\frac{1}{f_1} \Rightarrow \frac{1}{v_1}=\frac{1}{f_1}+\frac{1}{u_1}\)

⇒ \(\frac{1}{v_1}=\frac{1}{20}+\frac{1}{-15}\)

v1 – 60 cm

Now image formed (v1) acts as an object for L2.

For lens L2: \(\frac{1}{v_2}-\frac{1}{u_2}=\frac{1}{f_2} \Rightarrow \frac{1}{80}+\frac{1}{75}=\frac{1}{f_2} \Rightarrow \frac{1}{f_2}=\frac{31}{1200}\)

∴ \(\mathrm{f}_2=\frac{1200}{31} 38.71 \simeq 39 \mathrm{~cm}\)

Question 22. Describe the construction of a compound microscope. Derive an expression for its total magnification. Draw a ray diagram for the formation of an image by a compound microscope.

Answer:

Compound Microscope: Figure shows a ray diagram of a compound microscope. It consists of two convex lenses one nearer to the object is known as the objective and the other closest to the eye is the eyepiece lens. Here objective lens is of small focal length (f0) and small aperture whereas the eyepiece is also of small focal length but larger than the objective lens and relatively large aperture

Ray Optics And Optical Instruments Compound Microscope

The image A’ is formed by the objective lens L0 of object AB and the final image is A “B’.

Magnifying power (M) = \(\frac{\text { Angle subtended by the final image at eye }}{\text { Angle subtended by the object when it is placed at the least distance of distinct vision at eye }}\)

⇒ \(M=\frac{\beta}{\alpha} \quad\left\{\begin{array}{l}
\text { if } \alpha \text { and } \beta \text { are very smill. then } \\
\alpha=\tan \alpha \text { and } \beta=\tan \beta
\end{array}\right.\)

⇒ \(M=\frac{\tan \beta}{\tan \alpha}\)

∴ \(M=\frac{\left(\frac{A^{\prime \prime} B^{\prime \prime}}{D}\right)}{\left(\frac{A B}{D}\right)}\) = \(M=\frac{A^{\prime \prime} B^{\prime \prime}}{A B}\)

⇒ \(M=\frac{A^{\prime \prime} B^{\prime \prime}}{A^{\prime} B^{\prime}} \times \frac{A^{\prime} B^{\prime}}{A B} \Rightarrow M=m_e \times m_o \quad\left\{\begin{array}{l}
m_0=\frac{-v_0}{u_0} \\
m_c=\frac{v_e}{u_e}
\end{array}\right.\)

⇒ \(\mathrm{M}=\frac{-\mathrm{v}_{\mathrm{o}}}{\mathrm{u}_{\mathrm{o}}} \times \frac{\mathrm{v}_{\mathrm{c}}}{\mathrm{u}_{\mathrm{c}}}\) (1)

Applying lens Formula for eyepiece \(\)

⇒ \(\frac{1}{f_e}=\frac{1}{v_e}-\frac{1}{u_e} \quad\left\{\begin{array}{l}
v_e=-D \\
u_e=-u_e
\end{array}\right.\)

∴  \(\frac{1}{f_e}=-\frac{1}{D}+\frac{1}{u_e} \Rightarrow \frac{D}{f_e}=-1+\frac{D}{u_e}\) = \(\frac{\mathrm{D}}{\mathrm{u}_{\mathrm{e}}}=1+\frac{\mathrm{D}}{\mathrm{f}_{\mathrm{e}}}\) (2)

1. When the final image is formed at least the distance of district vision (Ve = -D)

⇒ \(M=\frac{-V_0}{u_0} \times \frac{D}{U_e}\)

∴ \(M=\frac{-V_0}{u_0}\left(1+\frac{D}{f_e}\right)\) → (3)

2. When the final image is formed at infinity (ue = fe)

∴ \(M=\frac{{-v_0}}{u_0} \times \frac{D}{1}\) (4)

Question 23.

  1. For a glass prism (μ = √3) the angle of minimum deviation is equal to the angle of the prism. Calculate the angle of the prism.
  2. Draw a ray diagram when the incident ray falls normally on one of the two equal sides of a right-angled isosceles prism having refractive index μ = √3.

Answer:

Given. δm = A

From \(\mu=\frac{\sin \left(\frac{A+\delta_m}{2}\right)}{\sin (A / 2)}\) = \(\frac{\sqrt{3}}{1}=\frac{\sin \left(\frac{A+A}{2}\right)}{\sin (A / 2)}=\frac{\sin A}{\sin (A / 2)}\)

⇒ \(\sqrt{3}=\frac{2 \sin (A / 2) \cos (A / 2)}{\sin (A / 2)}\) = \(\frac{\sqrt{3}}{2}=\cos \mathrm{A} / 2\)

⇒ \(\cos 30^{\circ}=\cos (\mathrm{A} / 2) \Rightarrow 30^{\circ}=\mathrm{A} / 2\)

∴ A = 60°

2. Given μ = √3 (Prism)

For total internal reflection, angle of incidence (i) > critical angle (ic)

i.e. i > ic

or sin i > sin ic

or \(\sin i>\frac{1}{\mu}\)

or \(\sin 45^{\circ}>\frac{1}{\mu}\)

or μ > 2

Hence, ray PQ suffers TIR and goes along path TS.

Ray Optics And Optical Instruments Total Internal Reflection

Question 24.

  1. Draw a schematic diagram of a reflecting telescope
  2. Slate the advantages of reflecting telescope over refracting telescope.

Answer:

Ray Optics And Optical Instruments Reflecting Telescope

Schematic diagram of a reflecting telescope (Cassegrain).

  1. Reflecting telescopes do not suffer from chromatic aberration.
  2. The intensity of light is higher in the case of a reflecting telescope.
  3. Reflecting telescope’s mirrors arc easier to mount.
  4. Manufacturing of mirrors is cheaper compared to lenses.

Question 25. A symmetric biconvex lens of radius of curvature R and made of glass of refractive index 1.5, is placed on a layer of liquid placed on top of a plane mirror as shown in the figure. An optical needle with its lip on the principal axis of the lens is moved along the axis until its real, inverted image coincides with the needle itself. The distance of the needle itself. The distance of the needle from the lens is measured to be x. On removing the liquid layer and repeating the experiment, the distance is found to be y. Obtain the expression for the refractive index of the liquid in terms of x and y.

Ray Optics And Optical Instruments Biconvex Lens

Answer:

Let μ1 denote the refractive index of the liquid. When the image of the needle coincides with the needle itself; its distance from the lens, equals the relevant focal length.

With a liquid layer present, the given set-up is equivalent to a combination of the given (convex) lens and a concave plane or piano concave ‘liquid ‘lens’.

We have \(\frac{1}{f}=(\mu-1)\left(\frac{1}{R_1}-\frac{1}{R_2}\right)\)

and \(\frac{1}{f}=\frac{1}{f_1}+\frac{1}{f_2}\)

⇒ \(\frac{1}{x}=\frac{1}{f_l}+\frac{1}{y}\)

as per the given data, we then have

⇒ \(\frac{1}{r_2}=\frac{1}{y}=(1.5-1)\left[\frac{1}{R}-\left(-\frac{1}{R}\right)\right]=\frac{1}{R} = \left\{\begin{array}{l}
\frac{1}{y}=\frac{1}{R}=\frac{1}{f_2} \\
f=x
\end{array}\right\}\)

∴ \(\frac{1}{x}=\left(\mu_1-1\right)\left(-\frac{1}{R}\right)+\frac{1}{y}=\frac{-\mu_1}{y}+\frac{2}{y}\)

∴ \(\frac{\mu_1}{y}=\frac{2}{y}-\frac{1}{x}=\left(\frac{2 x-y}{x y}\right) \text { or } \mu_1=\left(\frac{2 x-y}{x}\right)\)

Question 26. The figure shows a ray of light falling normally on the face AB of an equilateral glass prism having refractive index \(\frac{3}{2}\), placed in water of refractive index \(\frac{4}{3}\) Will this ray suffer total internal reflection on striking the face AC?

Ray Optics And Optical Instruments Ray Of Light

Answer:

The angle of incidence, of the ray, on striking the face AC is i = 60° (as in figure)

Also. the relative refractive index of glass, concerning the surrounding water, is \(\mu_{\mathrm{r}}=\frac{3 / 2}{4 / 3}=\frac{9}{8}\)

Also \(\sin \mathrm{i}=\sin 60^{\circ}=\frac{\sqrt{3}}{2}=\frac{1.732}{2}=0.866\)

For total internal reflection, the required critical angle, in this case, is given by.

⇒\(sin \mathrm{i}_{\mathrm{C}}=\frac{1}{\mu}=\frac{8}{9} \simeq 0.89\)

∴ i < ic

Ray Optics And Optical Instruments Relative Refractive Index Of Glass

Hence the ray would not suffer total internal reflection on striking the face AC.

[The student may just write the two conditions needed for total internal reflection without analysis of the given case]

Question 27. Establish a relation between focal length, distance of object and distance of image in concave mirror.

Answer:

Ray Optics And Optical Instruments Concave Mirror

u ⇒ distance between pole and object

v ⇒ distance between pole and image

f ⇒ focal length

In ΔA’FB’ and ΔRFQ

∠QFR = ∠A’FB’ and ∠A’B’ F = ∠RQF = 90°

∴ ΔA’FB’- ΔRFQ. so

\(\frac{A^{\prime} B^{\prime}}{Q R}=\frac{F B^{\prime}}{Q F} \Rightarrow \frac{A^{\prime} B^{\prime}}{A B}=\frac{F B^{\prime}}{Q F}\) (1) (from QR = AB)

Similarly ΔABC ∼ ΔA’B’c, hence

⇒ \(\frac{A^{\prime} B^{\prime}}{A B}=\frac{B^{\prime} C}{B C}\) → (2)

From eq (1) and(2)

∴ \(\frac{\mathrm{FB}^{\prime}}{\mathrm{QF}}=\frac{\mathrm{B}^{\prime} \mathrm{C}}{\mathrm{BC}}\)

Point Q is very close to P, Hence ⇒ QF ≈PF

⇒ \(\frac{P B^{\prime}-P F}{P F}=\frac{P C-P B^{\prime}}{P B-P C}\)

Applying sign convention, PB’ = -v, PF = -f, PC = -2f and PB = -u-0

⇒ \(\frac{-v-(-f)}{-f}=\frac{-2 f-(-v)}{u-(-2 f)}\)

On solving, uv – uf = vf

divide by uvf

∴ \(\frac{1}{\mathrm{f}}=\frac{1}{\mathrm{u}}+\frac{\mathrm{l}}{\mathrm{v}}\)  (This is mirror’s equation)

Question 28. Refractive indices of the given prism material for Red, Blue and Green colours arc 1 .39. 1 .48 and 1 .42 respectively. Trace the path of rays through the prism.

Ray Optics And Optical Instruments Refractive Indices Of The Prism

Answer:

For TIR

i > ic

sin i > sin ic

⇒ \(\sin i>\frac{1}{\mu}\)

cosec i < μ

R = 1 .39, μG = 1 .42, μB = 1 .48

Now → cosec 45° = √2 = 1 .414

So, μR < cosec i [Red colour will refract]

μB > cosec i [Blue colour will be internally reflected]

μG > cosec i [Green colour will be internally reflected]

Question 29. Two prisms ABC and DBC are arranged as shown in the figure

Ray Optics And Optical Instruments Refractive Indices Of The Prism.

The Ctritical angles for the two prisms concerning air are 41.1 and 45 respectively. Trace the path of the ray through the combination.

Answer:

Ray Optics And Optical Instruments Two Prisms

Question 30.

  1. An object is placed in front of a converging lens. Obtain the conditions under which the magnification produced by the lens is
    1. Negative and
    2. Positive.
  2. A point object is placed at 0 in front of a glass sphere. Show the formation of the image by the sphere.

Ray Optics And Optical Instruments The Critical Angles For The Two Prisms

Answer:

1. (1). For negative magnification object is placed beyond the focus:

⇒ \(m=\frac{v}{u}\)

using sign convention

∴ \(\mathrm{m}=-\frac{\mathrm{v}}{\mathrm{u}}\)

Ray Optics And Optical Instruments Converging Lens

(2). For positive magnification object is placed between the focus and the optical centre.

⇒ \(m=\frac{v}{u}\)

Using sign convention \(\mathrm{m}=\frac{-\mathrm{v}}{-\mathrm{u}}\)

∴ \(m=\frac{v}{u}\)

Ray Optics And Optical Instruments Negative Magnification Object

Ray Optics And Optical Instruments Glass Sphere

Refraction through spherical surface ABC

⇒ \(\frac{\mathrm{n}_2}{\mathrm{v}^{\prime}}-\frac{\mathrm{n}_1}{\mathrm{u}}=\frac{\mathrm{n}_2-\mathrm{n}_1}{\mathrm{R}} \quad\left\{\begin{array}{l}
\text { Refractive index of glass }=3 / 2 \\
\mathrm{u}=-3 \mathrm{r}
\end{array}\right.\)

⇒ \(\frac{\frac{3}{2}}{v^{\prime}}-\frac{1}{\left(-3 r\right)}=\frac{\left(\frac{3}{2}-1\right)}{r} = \frac{3}{2 v^{\prime}}=\frac{1}{2 r}-\frac{1}{3 r} = v^{\prime}=9 r\)

Refractive through spherical surface ADC

For refracting surface ADC, the image I’ acts as a virtual object and 1 is the final image

⇒ \(\frac{\mathrm{n}_2}{\mathrm{v}}-\frac{\mathrm{n}_1}{\mathrm{u}^{\prime}}=\frac{\mathrm{n}_2-\mathrm{n}_1}{\mathrm{R}} = \frac{1}{\mathrm{v}}-\frac{1.5}{\mathrm{u}^{\prime}}=\frac{1-1.5}{-\mathrm{r}}\) (u’ = 9r – 2r = 7r)

∴ \(\frac{1}{v}-\frac{1.5}{7 r}=\frac{0.5}{r} = \frac{1}{v}=\frac{1}{2 r}+\frac{1.5}{7 r} = \frac{1}{v}=\frac{1.5}{7 r}+\frac{0.5}{r}=\frac{1.5+3.5}{7 r} = v =\frac{7 r}{5}\)

Distance of final image from ‘B’

∴ \(\frac{7 r}{5}+2 r=\frac{17 r}{5}=3.4 \mathrm{r}\)

 CBSE Class 12 Physics Chapter 9 Long Questions And Answers

Question 1. Optical fibres Nowadays optical fibres are extensively used for transmitting audio and video signals through long distances. Optical fibres too make use of the phenomenon of total internal reflection. Optical fibre arc fabricated with high-quality composite glass or quartz fibres.

Each fibre consists of a core and cladding. The refractive index of the material of the core is higher than that of the cladding. When a signal in the form of light is directed at one end of the fibre at a suitable angle, it undergoes repeated total internal reflections along the length of the fibre and finally comes out at the other end.

Since light undergoes total internal reflection at each stage, there is no appreciable loss in the intensity of the light signal. Optical fibres are fabricated such that light reflected at one side of the inner surface strikes the other at an angle larger than the critical angle.

Even if the fibre is bent, light can easily travel along its length. Thus, an optical fibre can be used to act as an optical pipe.

Ray Optics And Optical Instruments Optical Fibers

(1). Which of the following statements is not true?

  1. Optical fibre is based on the principle of total internal reflection.
  2. The refractive index of the material of the core is less than that of the cladding.
  3. An optical fibre can be used to act as an optical pipe.
  4. There is no appreciable loss in the intensity of the light signal while propagating through optical fibre.

Answer: 2. The refractive index of the material of the core is less than that of the cladding.

(2). What is the condition for total internal reflection to occur?

  1. The angle of incidence must be equal to the critical angle.
  2. The angle of incidence must be less than the critical angle.
  3. The angle of incidence must be greater than the critical angle.
  4. None of the above

Answer: 3. Angle of incidence must be greater than the critical angle.

(3). Which of the following is not an application of total internal reflection?

  1. Mirage
  2. Sparkling of diamond
  3. Splitting of white light through a prism.
  4. Reflects the prism.

Answer: 3. Splitting of white light through a prism.

(4). Optical fibres are used extensively to transmit:

  1. Optical signal
  2. Current
  3. Sound waves
  4. None of the above

Answer: 1. Optical signal

Question 2. The total internal reflection of the light is used in polishing diamonds to create a sparking brilliance. By polishing the diamond with specific cuts, it adjusted most of the light rays approaching the surface arc incident with an angle of incidence more than the critical angle. Hence, they suffer multiple reflections and ultimately come out of the diamond from the top. This gives the diamond a sparking brilliance.

Ray Optics And Optical Instruments Polishing Diamonds To Create A Sparking Brilliance

(1). The refractive index for a diamond is

  1. 1.41
  2. Same as glass
  3. 2.42
  4. 1

Answer: 3. 2.42

(2). The basic reason for the extraordinary sparkle of a suitably cut diamond is that

  1. It has a low refractive index
  2. It has high transparency
  3. It has a high refractive index
  4. It is very hard

Answer: 3. It has a high refractive index

(3). The extraordinary sparkling of diamond

  1. Docs do not depend on their shape
  2. Depends on its shape
  3. Has no fixed reason
  4. None

Answer: 4. None

(4). Optical fibre cables work on the principle of

  1. Dispersion of light
  2. Refraction of light
  3. Total internal reflection
  4. Interference of light

Answer: 3. Total internal reflection

Question 3. A compound microscope consists of two converging lenses. One of them, of a smaller aperture and smaller focal length is called an objective and the other of a slightly larger aperture and slightly larger focal length is called an eye-piece. Both lenses are fitted in a tube with an arrangement to vary the distance between them. A tiny object is placed in front of the objective at a distance slightly greater than its focal length. The objective produces the image of the object which acts as an object for the eye-piece. The eyepiece, in turn, produces the final magnified image.

(1). In a compound microscope the images formed by the objective and the eye-piece are respectively.

  1. Virtual, real
  2. Real, virtual
  3. Virtual, virtual
  4. Real, real

Answer: 2. Real, virtual

(2). The magnification due to a compound microscope does not depend upon:

  1. The aperture of the objective and the eye-piece
  2. The focal length of the objective and the eye-piece
  3. The length of the tube
  4. The colour of the light used

Answer: 1. The aperture of the objective and the eye-piece

(3). Which of the following is not correct in the context of a compound microscope?

  1. Both the lenses are of short Focal lengths.
  2. The magnifying power increases by decreasing the local lengths of the two lenses.
  3. The distance between the two lenses is more than (f0 + fc)
  4. The microscope can be used as a telescope interchanging the two lenses.

Answer: 4. The microscope can be used as a telescope interchanging the two lenses

(4). A compound microscope consists of an objective of 10X and an eye-piece of 20X. the magnification due to the microscope would he:

  1. 2
  2. 10
  3. 30
  4. 200

Answer: 4. 200

(5). The focal length of the objective and eye-pic of a compound microscope arc is 1.2 cm and 3.0 cm respectively. The object is placed at a distance of 1.25 cm from the objective. If the final image is formed at infinity, the magnifying power of the microscope would be:

  1. 100
  2. 150
  3. 200
  4. 250

Answer: 3. 200

Question 4.

  1. Plot a graph to show the variation of the angle of deviation as a function of the angle of incidence for light passing through a prism. Derive an expression for the refractive index of the prism in terms of the angle of minimum deviation and the angle of the prism.
  2. What is the dispersion of light? What is its cause?
  3. A ray of light incident normally on one face of a right-angled isosceles prism is reflected as shown. What must be the minimum value of the refractive index of glass? Give relevant calculations.

Ray Optics And Optical Instruments Right Angled Isosceles Prism Is Totally Reflected

Answer:

Ray Optics And Optical Instruments Angle Of Minimum Deviation And Angle Of Prism

Let PQ and RS be incident and emergent rays. Let the incident ray get deviated by (δ) in a prism.

i.e. ∠TMS = δ

δ1 and δ2 are deviations produced at surfaces AB and AC respectively.

∴ δ = δ1 + δ2

δ = ( i1 – r1 ) + ( i2 – r2 )

δ = ( i1 +i2 )- ( r1 +r2 ) → (1)

In quadrilateral AQNR,

A + ∠QNR = 180° ( ∵ QN, RN are normal)

Also, in ΔQNR, ∠QNR + r1 + r2 = 180°

δ = r1 + r2 → (2)

From eq (1) and (2), we get

δ = ( i1 +i2 )- A →(3)

The angle of deviation produced by the prism varies with the angle of incidence. When the prism is adjusted at an angle of minimum deviation, then

i1 = i2 = i (suppose)

at δ = δm

⇒ r= r2 = r (suppose)

From (1) and (2) we have,

δm = 2i – 2r

and 2r = A

⇒ \(i=\frac{A+\delta_{m}}{2}\)

r = A/2

∴ Refractive index of material of prism is \(\mu=\frac{\sin \mathrm{i}}{\sin \mathrm{r}}=\frac{\sin \left(\frac{\mathrm{A}+\delta_{\mathrm{m}}}{2}\right)}{\sin \left(\frac{\mathrm{A}}{2}\right)}\).

2. The splitting of white light into bands of seven different colours (V, I, B, g, Y, O, R) is called dispersion of white light.

Cause: Different colours travel with velocity while passing through a prism so they get separated.

Ray Optics And Optical Instruments Right Angled Isosceles Prism Is Totally Reflected.

From geometry, the angle of incidence at the surface (AC) is 45°. Now as shown ray MN gets reflected at angle 45, i.e, i > ic

From \(\mu=\frac{1}{\sin i_c}=\frac{1}{\sin 45^{\circ}}=\sqrt{2}\)

Question 5.

  1. Draw a ray diagram to show the image formation by a combination of two thin convex lenses in contact. Obtain the expression for the power of this combination in terms of the focal lengths of the lenses.
  2. A ray of light passing from the air through an equilateral glass prism undergoes minimum deviation when the angle of incidence is \(\left(\frac{3}{4}\right)^{\mathrm{th}}\) of the angle of prism. Calculate the speed of light in the prism.

Answer:

Ray Optics And Optical Instruments Focal Lengths Of The Lenses

The object is placed at point O. whose image is formed at me, by the first lens. As image I1 is real, it works as a virtual object for second lens B, producing the final image at I.

Since the lenses are thin, assume the optical centres to be coincident. Let this central point be p.

For the image formed by lens A.

\(\frac{1}{v_1}-\frac{1}{u}=\frac{1}{f_1}\) → (1)

Similarly, for the lens B,

\(\frac{1}{v}-\frac{1}{v_1}=\frac{1}{f_2}\) → (2)

Add (1) and (2) we get,

\(\frac{1}{v}-\frac{1}{u}=\frac{1}{f_1}+\frac{1}{f_2}\)

If a lens system is taken as equivalent to a single lens of focal length f, we get.

\(P=\frac{1}{f}=\frac{1}{f_1}+\frac{1}{f_2}\) → (3)

In terms of power, equation (3) can be written as,

P = P1 + P2

Where P is the net power of this combination.

2. Given: (A = angle of prism)

  • ABC is an equilateral triangle. [A = 60°]
  • \(\angle \mathrm{i}=\frac{3}{4} \mathrm{~A}\)

Ray Optics And Optical Instruments Equilateral Triangle

we know that,

δ =i + c- A

Now in the condition of min. deviation,

i = e, therefore we can write,

δm = i +i- A

or \(\delta_{\mathrm{m}}=2 \mathrm{i}-\mathrm{A} \text { or } \delta_{\mathrm{m}}=2\left(\frac{3 \mathrm{~A}}{4}\right)-\mathrm{A}\)

⇒ \(\delta_{\mathrm{m}}=\frac{3 \mathrm{~A}}{2}-\mathrm{A}=\frac{\mathrm{A}}{2}=30^{\circ}\)

⇒ δm = 30°

Now, \(\mu=\frac{\sin \left(\frac{A+\delta_m}{2}\right)}{\sin \left(\frac{A}{2}\right)}=\frac{\sin \left(\frac{60^{\circ}+30^{\circ}}{2}\right)}{\sin \left(\frac{60^{\circ}}{2}\right)}\)

⇒ \(\mu=\frac{\sin 45^{\circ}}{\sin 30^{\circ}}=\sqrt{2}\)

So, \(v=\frac{c}{\mu}=\frac{3 \times 10^8}{\sqrt{2}}=2.1 \times 10^8 \mathrm{~m} / \mathrm{s}\)

Question 6. A point object O on the principal axis of a spherical surface of radius of curvature R separating two media of refractive indices ni and m forms an image T.

Prove that: \(\frac{n_2}{v}-\frac{n_1}{u}=\frac{n_2-n_1}{R}\)

Ray Optics And Optical Instruments Principal Axis Of A Spherical Surfaces

Answer:

Assumptions:

  • The Aperature of the spherical refracting surface is small.
  • The object is a point object and lies on the principal axis.
  • Incident ray, refracted ray and normal to the spherical surface make small angles with PA.

Let, XPY = Convex spherical refracting surface.

0 = Point object in rarer medium

I = Real image in a denser medium

Ray Optics And Optical Instruments Refractive And Normal Rays To The Spherical Surfaces

From ΔAOC, i = α + γ

From ΔAIC, γ = r + β ⇒ r = γ – β

From snell’s law, \(\frac{\sin i}{\sin r}=\frac{n_2}{n_1} ⇒ n_1 \sin i=n_2 \sin r\)

Since the angles are small,

∴ n1 i = n2 r

Substituting for i and r, in the above eqn, we get

⇒ n1 (α + γ) = n2 (γ – β)

or \(n_1\left\{\frac{\mathrm{AM}}{\mathrm{PO}}+\frac{\mathrm{AM}}{\mathrm{MC}}\right\}=\mathrm{n}_2\left\{\frac{\mathrm{AM}}{\mathrm{MC}}-\frac{\mathrm{AM}}{\mathrm{MI}}\right\}\)

Since the aperature is small,

∴ MC = PC, MI = PI

∴ \(\left\{\frac{n_1}{P O}+\frac{n_1}{P C}\right\}=\left\{\frac{n_2}{P C}-\frac{n_2}{P l}\right\}\)

Acc. to sign convention,

PO = -u. PC = R, PI = v

∴ \(\left\{\frac{n_1}{-u}+\frac{n_1}{R}\right\}=\left\{\frac{n_2}{R}-\frac{n_2}{v}\right\}\)

or. \(\frac{n_2}{v}-\frac{n_1}{u}=\frac{n_2-n_1}{R}\)

Question 7.

  1. Derive lens maker’s formula. Draw the necessary diagram.
  2. A convex lens is placed over a plane mirror. A pin is now positioned so that there is no parallax between the pin and its image formed by this lens-mirror combination. How will you use this observation to find the focal length of the lens? Explain briefly.

Answer:

1. Lens maker’s formula

∴ \(\frac{1}{f}=(n-1)\left[\frac{1}{R_1}-\frac{1}{R_2}\right]\)

Assumptions:

  1. The lens is considered a thin lens.
  2. An object is a point object which is situated on the principal axis.
  3. The aperture of the lens is small.
  4. Incident and refracted rays make a small angle with the principal axis.

Consider a thin convex lens of absolute refractive index n2 placed in a rarer medium of absolute refractive index n1. Also, R1 and R2 are the radii of curvature of surfaces XP1 Y and XP2 Y respectively.

Ray Optics And Optical Instruments Lens Maker's

For refraction at surface XP1 Y:

‘O’ is the object and I’ is its real image.

Using formula,

⇒ \(\frac{n_2}{v}-\frac{n_1}{u}=\frac{n_2-n_1}{R}\) we get,

⇒ \(\frac{n_2}{v^{\prime}}-\frac{n_1}{u}=\frac{n_2-n_1}{R_1}\) → (1)

For refraction at surface XP2 Y:

F is the virtual object &I is its real image (final image).

Using formula

⇒ \(\frac{n_1}{v}-\frac{n_2}{u}=\frac{n_1-n_2}{R}\)

⇒ \(\frac{n_1}{v}-\frac{n_2}{v^{\prime}}=\frac{n_1-n_2}{R_2}\) → (2)

Adding equations (1) and (2). we get

⇒ \(n_1\left(\frac{1}{v}-\frac{1}{u}\right)=\left(n_2-n_1\right)\left[\frac{1}{R_1}-\frac{1}{R_2}\right]\)

⇒ \(\frac{1}{v}-\frac{1}{u}=\frac{n_2-n_1}{n_1}\left[\frac{1}{R_1}-\frac{1}{R_2}\right]\)

or \(\frac{1}{f}=\frac{1}{v}-\frac{1}{u}=\left(\frac{n_2}{n_1}-1\right)\left[\frac{1}{R_1}-\frac{1}{R_2}\right]\)

or \(\frac{1}{f}=(n-1)\left[\frac{1}{R_1}-\frac{1}{R_2}\right]\) (\(\frac{n_2}{n_1}=n_1=n\))

2. The rays must fall normally on the plane mirror so that the image of the pin coincides with itself.

Ray Optics And Optical Instruments Convex Lens Is Placed Over A Plane Mirror

∴ P is the position of the locus of the lens. i.e.

Distance OP = focal length