NCERT Exemplar Solutions Class 6 Science Light Shadows and Reflection

Multiple Choice Questions (MCQs)

Question 1:  Observe the picture given in the figure carefully.

A patch of light is obtained at B when the torch is lighted as shown. Which of the following is kept at position A to get this patch of light?

(a) A wooden board 

(b) A glass sheet

(c) A mirror                

(d) A sheet of white paper

Solution 1:  The right thing for which selection is made is (c) A mirror. 

In order to receive a patch of light, a mirror is kept at position A since only a mirror can change the path of light that falls on it, i.e. it induces reflection.

Question 2:  Four students A, B, C and D looked through pipes of different shapes to see a candle flame as shown in figure.

Who will be able to see the candle flame clearly?
(a) A    (b) B   (c) C    (d) D

Solution 2: The right thing for which selection is made is (d) D. 

Since light travels along a straight line, Student D will be able to see the candle flame clearly. Students A, B and C, however, will not be able to clearly see the flame because the tubes are not straight.

Question 3:  Which of the following is/are not always necessary to observe a shadow?
(a) Sun   (b) Screen    (c) Source of light    (d) Opaque object

Solution 3:  The right thing for which selection is made is (a). 

To observe a shadow, Sun is not always required since any light source, an opaque object and a screen are only necessary enough to see a shadow.

Question 4:  Paheli observed the shadow of a tree at 8:00 am, 12:00 noon and 3:00 pm. Which of the following statements is closest to her observation about the shape and size of the shadow?
(a) The shape of the shadow of the tree changes but the size remains the same.
(b) The size of the shadow of the tree changes but the shape remains the same.
(c) Both the size and shape of the shadow of the tree changes.
(d) Neither the shape nor the size of the shadow changes. 

Solution 4:  The right thing for which selection is made is (c) Both the size and shape of the shadow of the tree changes. 

Both the size and shape of the tree's shadow will be modified because the lengths of the tree's shadows will be longer than their actual length at 8:00 a.m. and 3:00 p.m. and point to the west and east directions, respectively. At 12:00 noon, however, the sun will be high in the sky just above the tree, so the tree's shadow will be low.

Question 5:  Which of the following can never form a circular shadow?

(a) A ball   

(b) A flat disc

(c) A shoe box  

(d) An ice-cream cone

Solution 5:  The right thing for which selection is made is (c) A shoe box.   

A shoe box will never produce a circular shadow. It does not have a circular form under any circumstances. However, a circular shadow can form a ball, a flat disc and the base of an ice-cream cone.

Question 6:  Two students while sitting across a table looked down onto its top surface. They noticed that they could see their own and each other’s image. The table top is likely to be made of

(a) unpolished wood  

(b) Red stone

(c) glass sheet          

(d) Wood top covered with cloth

Solution 6:  The right thing for which selection is made is (c) glass sheet. 

Since only a glass sheet can display the pictures of both students, which can be seen by both of them, the table top must be made of glass sheet.

Very Short Answer Type Questions

Question 7:  You have 3 opaque strips with very small holes of different shapes as shown in figure. If you obtain an image of the sun on a wall through these holes, will the image formed by these holes be the same or different?

Solution 7:  In all three cases, a small circular image of the sun will be obtained since the holes will serve as a pinhole camera, whatever their shapes are. Also, when the light travels along a straight direction, the sun's picture will therefore remain the same.

Question 8:  Observe the picture given in figure. A sheet of some material is placed at position P, still the patch of light is obtained on the screen. What is the type of material of this sheet?

Solution 8:  At location P, a sheet of transparent material is positioned since only a transparent material enables light to pass through it undisturbed and the patch of light is thus obtained on the screen at the same spot.

Question 9:   Three torches A, B and C shown in figure are switched ON one by one. The light from which of the torch will not form a shadow of the ball on the screen?

Solution 9:  On the screen, the light from torch C will not shape a shadow because light travels in a straight path and forms the shadow on the same path it comes from.

Question 10:  Look at the given figure.

Will there be any difference in the shadow formed on the screen A and B?

Solution 10:  No, because the length and width of an object are the same in both cases, there will not be any difference. 

Short Answer Type Questions

Question 11:  Correct the following statements.
(a) The color of the shadow of an object depends on its color.
(b) Transparent objects allow light to pass through them partially.

Solution 11:
(a) The color of an object's shadow is not dependent on its object's color. Regardless of any colored object, it is always black.

(b) Transparent objects enable most of the light to pass through them, or translucent objects enable partial passage of light through them.

Question 12:  Suggest a situation where we obtain more than one shadow of an object at a time.

Solution 12:   Using various light sources, more than one shadow or multiple shadows of an object can be obtained, i.e. several player shadows are seen due to flood (stadium) lights in the stadium during a night match being played in a stadium. 

Question 13:  On a sunny day, does a bird or an aero plane flying high in the sky cast its shadow on the ground? Under what circumstances, can we see their shadow on the ground?

Solution 13:   No, because they are very high in the sky, they do not cast any shadow on the ground. They can only cast shadows if they are somewhat lower in height, i.e. we can see their shadows if they are close to the ground. 

Question 14:  You are given a transparent glass sheet. Suggest any two ways to make it translucent without breaking it.

Solution 14:   Transparent sheets of glass can be translucent in two ways:

i)        By rubbing it and making it rough on the ground.

ii)       Through the implementation of oil, grease or butter.

Question 15:  A torch is placed at two different positions A and B one by one as shown in figure.

The shape of the shadow obtained in two positions is shown in the given figure.

Match the position of the torch and shape of the shadow of the ball.

Solution 15:   The torch's position A and B will form the football's shadow (a) and shadow (b) respectively. Here, the difference in ball shadow shapes (a) and (b) is due to the difference in the ball torch positions A and B. The form of the shadow (a) is greater than that of the shadow (b) of the ball only because the screen, the torch in position A and the ball are in the same straight line.

Question 16:  A student covered a torch with red cello phone sheet to obtain red light. Using the red light, she obtains a shadow of an opaque object. She repeats this activity with green and blue lights. Will the color of the light affect the shadow? Explain.

Solution 16:   The shadow is just a lack of light in this place. The colors of the object do not affect the shadow because the amount of light that prevents it from passing remains the same. The shadow is only affected by the object's shape. The shadow will be large if the object is big and vice versa.

Question 17: Is air around us always transparent? Discuss.

Solution 17:  We can see the objects clearly through the air, which means that without any disturbance we can observe all the objects in their original shapes and sizes, which means that the environment around us, which is just air, must be transparent.

But it does not remain transparent when thick smoke, thick clouds, etc., are present in the air.

Question 18:  Three identical towels of red, blue and green color are hanging on a clothes line in the sun. What would be the color of shadows of these towels?

Solution 18:   Shadow of an object does not change on changing its color. Shadow will always show the absence of light at that place. So, the color of shadow will remain same in all the cases. Thus, the shadows of all the towels are black in color.

Question 19:  Using a pinhole camera, a student observes the image of two of his friends, standing in sunlight, wearing yellow and red shirts, respectively. What will be the colors of the shirts in the image?

Solution 19:   The shirt colors will remain the same. We see them on the screen because the pinhole camera forms the same colored but upside down image of the object. In this way, the yellow shirt forms a yellow image and the red shirt forms a red image.

Question 20:  In given figure, a flower made of thick colored paper has been pasted on the transparent glass sheet. What will be the shape and color of shadow seen on the screen?

Solution 20:  The flower shape on the screen will be the same as the flower shape, but the flower shadow is black in color. 

Long Answer Type Questions

Question 21:  A football match is being played at night in a stadium with flood lights ON. You can see the shadow of a football kept at the ground but cannot see its shadow when it is kicked high in the air. Explain.

Solution 21:   When the screen and the object are very far from each other, the shadow of an object cannot be caught. It's the same case here. Here, when football is kicked high up in the air, the shadow of the football cannot be seen on the ground (which acts as a screen).

This happens because the shadow gets smaller and smaller as we take the object away and away from the screen, and a moment arrives when it disappears entirely from the screen.

Question 22:  A student had a ball, a screen and a torch in working condition. He tried to form a shadow of the ball on the screen by placing them at different positions. Sometimes, the shadow was not obtained. Explain.

Solution 22:  Sometimes, due to improper arrangement of the light source (torch), object and screen, the shadow of the object (ball) may not be created. It may be for the following reasons:

(a) The ball screen.

(b) The direction of the light beam from the torch falling on the ball is parallel to the screen

(c) The ball is kept away from the torch.

Only if the screen, torch and ball are in the same straight line will a precise ball shadow be formed (as shown in the following figure).

Question 23:   A sheet of plywood, a piece of muslin cloth and that of a transparent glass, all of the same size and shape were placed at A one by one in the arrangement shown in figure. Will the shadow be formed in each case? If yes, then how will the shadow on the screen be different in each case? Give reasons for your answer.

Solution 23:  Yes, the shadow will be created in each case, but the darkness of the shadow will be distinct in all situations.

i)        In the case of a transparent sheet of glass, much of the light will pass through the glass. Therefore, the darkness of the shadow will be very thin.

ii)       The bulk of light would be reflected in the case of muslin fabric. So the shadow will be darker than the sheet of glass that is transparent.

iii)     In the case of plywood, all light is completely stopped by the plywood.

So, in this case, the strength of darkness will be the highest.