Intro to Thin Lenses

Q.

A converging lens is used to form an image on a screen. When the upper half of the lens is covered by an opaque screen, what happens to the image?

1. Half of the image will disappear

2. No part of the image will disappear

3. The intensity of the image will increase

4. The intensity of the image will decrease

Q. The lens in spectacles can be approximated to thin lens.

1. True
2. False

Q. A converging lens is used to form an image on a screen. When upper half of the lens is covered by an opaque screen

1. Half the image will disappear
2. Complete image will be formed of same intensity
3. Half image will be formed of same intensity
4. Complete image will be formed of decreased intensity

Q. A convex lens of focal length f is placed at origin. Object is placed on negative x-axis anywhere between $-\infty$ to $+\infty$. Choose correct graph between 'u' and 'v'.

1. 
2. 
3. 
4.