CBSE Class 8 Science Chapter 13 Light Activities

CBSE Class 8 Science Chapter 13 Light Activities Activity 1

Aim To understand the reflection by a plane mirror.

Material Required Drawing board, white sheet, comb, plane mirror, black paper, and a torch.

Procedure

1. Fix the white sheet of paper on the drawing board.
2. Take the comb and close all its holes except one present in the middle with the help of black paper.
3. Hold the comb perpendicular to the drawing board.
4. Now, take the torch and throw light on the comb. Light must fall on the opening of the comb.
5. 5. You will see a ray of light falling on the drawing board. Place a plane mirror in the path of light and observe what happens to the ray coming from the comb.

” Cbse Class 8 Science Chapter 13 Activities “

Conclusion The light ray strikes with the mirror and changes its path. The ray coming from the comb is incident ray and the ray going after striking the mirror is reflected ray.

Read And Learn More CBSE Class 8 Science Activities

CBSE Class 8 Science Second Law Of Reflection Activity 2

Aim To understand the second law of reflection.

Material Required A chart paper (white) , a plane mirror, a comb, black paper and a torch.

Procedure

1. Spread the white chart paper on the table such that it extends little beyond the edge of the table.
2. Close all the holes of the comb with black paper, except one at the middle.
3. Place plane mirror and comb perpendicular to the table as shown
4. You will see the incident ray and reflected ray on the while chart paper. Now, bend the chart paper at the end of the table.
5. You will not see the reflected ray on the bended portion of the chart paper. Now, bring the paper back to its original position. You will again see the reflected ray.

” Light Activities For Class 8 Cbse “

Conclusion We have concluded that the incident ray, reflected ray and the normal all lie in the same plane.

” Reflection Of Light Class 8 “

CBSE Class 8 Science Formation Of Image By A Plane Mirror Activity 3

Aim To study the formation of image by a plane mirror.

Material Required Drawing board, a white paper, a plane mirror, a pencil and a ruler.

Procedure

1. Paste the white paper on the drawing board.
2. Consider that an object is at O. Now, draw two rays OM and OH incident on the mirror.
3. Draw two reflected rays MN and HG by making angle of reflection equal to angle of incidence. Extend these reflected rays further. You will find that they do not meet.
4. Now, extend the two reflected rays using a pencil and ruler behind the mirror (dotted lines). Mark the point 1 where they meet.
5. Since, the reflected rays do not actually meet at 1, we say that it is a virtual image.
6. Measure the distance of object (PO) and distance of image (PI) from the mirror (PQ).

” Laws Of Reflection Class 8 “

Conclusion

1. The distance of object from the mirror is same as the distance ofthe image from the mirror i.e. PO = PI.
2. The image formed by plane mirror is virtual.

CBSE Class 8 Science Properties Of Reflection From An Irregular Surface Activity 4

Aim To study the properties of reflection from an irregular surface using laws of reflection.

Material Required White sheet, ruler, protractor and a pencil.

Procedure

1. Drawa rough surface on the white sheet as shown in figure (a).

” Image Formation By Plane Mirror “

1. Draw parallel rays which fall on this surface. These rays arc incident rays.
2. Draw perpendicular line at every point of incident on the surface.
3. Now, measure the angle between normal and incident ray for every ray. This is angle of incidence.
4. Draw angle of reflection which is equal to the angle of incidence as shown in figure (b), then draw reflected rays.

Conclusion Incident rays are parallel but reflected rays are not parallel. Hence, irregular surfaces produce irregular or diffused reflection.

CBSE Class 8 Science Number Of Images Formed By Two Mirrors Activity 5

Aim To study the number of images formed by two mirrors inclined at some angle.

Material Required Two mirrors, any small object like pen, pencil or rubber.

Procedure

• Place two mirrors at right angles to each other with their edges touching.
• Place the object in between the mirrors. We can see two images in the mirrors.

” Dispersion Of Light Into Vibgyor “

• Now, change the angle between mirrors (like 45°,60°,120°,180°). You can set angles with the help of a protractor.
• Note down the number of images formed in each case.

Conclusion

1. When angle between mirrors is greater than 90°, then two Images are formed.
2. When the angle between mirrors is less than 90“, then number of images increases.

CBSE Class 8 Science Build A Kaleidoscope Activity 6

Aim To build a kaleidoscope.

Material Required Three rectangular mirror stripes (15 cmx 4 cm), circular cardboard tube, cardboard disc, a circular transparent glass plate, a circular grounded glass plate and several small pieces ofcoloured glass or bangles.

Procedure

1. Take the three rectangular mirror strips and join them to form a hollow prism with their reflecting surface facing each other.
2. Fix this prism in a circular cardboard tube and close one end of the tube by a cardboard disc. Make a small hole in this disc.
3. Close the other end of prism with the circular glass plate.
4. Put several pieces of coloured bangles on this plate.
5. Close the end oftube with the grounded circular glass plate. Now, your kaleidoscope is ready.
6. Now, see through the hole and rotate the cardboard

” Persistence Of Vision Experiment “

Conclusion We observed different patterns in the kaleidoscope every time. These patterns are visible due to multiple reflection by glass strips.

Activity 7

Aim To show that sunlight is made up of seven colours.

Material Required A howl filled with water, a plane strip of mirror, white paper.

Procedure

1. Place the howl filled with water on a table. Now, place a strip of mirror partially immersed into the water.
2. Place this arrangement near a window such that direct sunlight falls on the mirror.
3. Adjust the mirror in such a way that the reflected light fall on a wall.
4. Place the white paper where the reflected light fall on the wall.
5. Observe the colours of reflected light.

” Kaleidoscope Construction Class 8 “

Conclusion Sunlight is made up ofseven colours named as violet,indigo, blue, green, yellow, orange and red. In short form, it is known as VIBGYOR (first letter ofevery colour) and the splitting of light into its constituent colours is known as dispersion of light.

CBSE Class 8 Science The Effect Of Light Activity 8

Aim To observe the effect of light on the size of pupil.

Material Required A torch.

Procedure

1. Look into your friends eye and observe the size of pupil.
2. Now, throw light on her eye with the torch. Now, observe the size of pupil.
3. Now, switch OFF the light and observe the size of pupil once again.

” Cbse Class 8 Science Experiments “

Conclusion

1. Size of pupil is small when the torch is ON. This happens to protect eye from intense light.
2. Size ofpupil increases when the torch is switched off. This happens to gather more light to see objects clearly.

CBSE Class 8 Science Existence Of Blind Spot Activity 9

Aim To demonstrate the existence of blind spot in the eye.

Material Required A white paper strip and a marker.

Procedure

1. Make a round mark and a cross mark on a sheet of paper with the help of marker. The round mark should be or the right side of the cross mark.
2. Distance between the two marks should be 6-8 cm.
3. Now, hold this paper at an arm’s length from the eye.
4. Close your left eye and look continuously on the cross mark.
5. Move the sheet slowly towards your eye and keep your eye on the cross.
6. Move the sheet towards your eye until the round mark disappears.
7. Now, close your right eye and look at the round mark, then repeat step 5 and 6

” Plane Mirror Reflection Activity “

Conclusion While bringing the strip towards the eye at some point, one mark disappears.

CBSE Class 8 Science The Persistence Of Vision Activity 10

Aim To understand the persistence of vision.

Material Required A square piece of cardboard, a long thread and a pencil.

Procedure

1. Make two holes in the cardboard as shown in figure.
2. Draw a cage on one side of the cardboard and a bird on the other side of the cardboard.
3. Now, insert the string in the hole as shown in the diagram.
4. Now, hold the free ends of the thread on both sides and twist it in such a way that the cardboard rotates very fast. Now, write your observation.

” Virtual Image Formation Class 8 “

Conclusion The bird appears as it is in the cage but it is on the other side of the cardboard.