Class 7 Science Chapter 15 | Light | Expected Questions

1. With an activity explain that light travels along a straight line.

Place a lighted candle on a table. Now look at the candle through a straight light. The candle is visible now. Now take a bent pipe and look at the candle. The candle is not visible through the bent pipe. This shows that light travels along a straight line.

2. What is reflection of light?

When light falls on a shiny or polished surface like a mirror, its direction changes. This change in direction of light is called the reflection of light.

3. What is an erect image?

An image formed by a plane mirror is always upright and of the same size as the object. Such an image is called an erect image.

4. What is a real image?

An image formed on a screen is called a real image.

5. What is a virtual image?

The image formed by a plane mirror cannot be obtained on a screen. This is called a virtual image.

6. Explain with an activity that the image formed by a concave mirror can be obtained on a screen.

Take a concave mirror and place it facing the sun. Try to get the light reflected by the mirror on a sheet of paper. Adjust the distance between the mirror and the paper so that you can get a sharp bright spot on it. This bright spot is the image of the sun.

7. The image formed by a concave mirror can be …………………………………. than the object.

Smaller or larger

8. What are some uses of concave mirrors?

Concave mirrors have several uses. Doctors use them to examine eyes, ears, nose and throat. Dentists often use them to get an enlarged image of the teeth. The reflectors of torches and headlights of cars and scooters are also concave in shape.

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9. Why are convex mirrors used as sideview mirrors in cars and buses?

Convex mirrors can produce images of objects spread over a large area. Hence, they are used as sideview mirrors because they help drivers to see the traffic behind them.

10. Why are convex lenses called converging lens?

A convex lens converges the light falling on it. Hence, it is called a converging lens.

11. Why are concave lenses called diverging lenses?

A concave lens diverges the light. Hence, it is called a diverging lens.

12. The image formed by a concave lens is always ………………………….. than the object.

Smaller

13. How many colors are present in sunlight?

Seven

14. What are the seven colors in sunlight?

Violet, indigo, blue, green, yellow, orange and red.

15. Prove with an activity that the sunlight is a mixture of seven colors

Take a glass prism and put it in a dark room. Allow a narrow beam of light to fall on the face of the prism. Let the light coming out of the other face to fall on a white wall. You will observe colors similar to that of the rainbow on the wall. This experiment proves that sunlight is a mixture of seven colors.

16. The image formed by a plane mirror is …………………………….

Erect and virtual

17. A concave mirror forms ………………………… and ………………………… images.

Real and inverted

18. A concave mirror produces an erect and magnified image when the object is ………………………….. to the mirror.

Very close

19. An image formed by a convex mirror is ………………………….. in size.

Smaller

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