NCERT Class VI Science Solutions: Chapter 11 – Light Shadows and Reflections Part 5

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Question 18:

Is air around us always transparent? Discuss.

Answer:

Air around us is transparent but when thick smoke, thick clouds, etc. are present in the air it does not remain transparent.

Question 19:

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

Answer:

The colour of shadows of all three towels will be the same.

Question 20:

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

Answer:

The colours of the image of the shirts will be the same as the colour of the shirt.

Question 21:

In Fig, a flower made of thick coloured paper has been pasted on the transparent glass sheet. What will be the shape and colour of shadow seen on the screen?

Image of a flower made of thick coloured paper has been pasted on the transparent glass sheet

Thick Coloured Paper Pasted on Transparent Glass

Image of a flower made of thick coloured paper has been pasted on the transparent glass sheet

Answer:

The shadow formed will be dark and of the shape of the flower along with the stalk.

LONG ANSWER QUESTIONS

Question 22:

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.

Answer:

We can see the shadow of football lying on the ground because the ground acts as a screen for it. However, when the football is kicked high, the ground, which is acting as a screen is away from the football, hence no shadow of the football will be formed on the ground.

Question 23:

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.

Answer:

Some of the reason can be

  1. The screen is away from the ball.

  2. The beam of light from the torch is falling parallel to the screen on the ball.

  3. The torch is kept away from the ball.

Question 24:

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 Fig. Will the shadow he formed in each case. If yes, how will the shadow on the screen be different in each case? Give reasons for your answer.

Answer:

Shadow will not be formed in each case. Shadow will be formed by the sheet of plywood and the piece of muslin cloth.

The sheet of plywood will form a dark shadow as it blocks the path of light completely.

The piece of muslin cloth will form a lighter shadow as it allow light to pass through it partially.

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