Light: Mirrors and Lenses MCQs for UPSC Prelims

On walking from bright sunlight into a dim room, a person can see almost nothing at first, and things slowly become visible over the next minute. This happens because

1. A the retina has been permanently damaged by the sunlight
2. B the opening in the iris takes time to widen and let in more light
3. C the room really does grow brighter minute by minute
4. D the eye lens turns into a mirror in the dark

A student examines a leaf with a magnifying glass and then slowly raises the lens away from the leaf. Beyond a certain height the leaf suddenly appears upside down. This shows that

1. A the lens has changed into a concave lens as it was lifted
2. B the eye stops working properly at that height
3. C a convex lens gives an enlarged upright image only while the object is close enough to it
4. D the leaf itself has turned over on the table

For a plane mirror, the distance of the image behind the mirror is

1. A always fixed at $1\ \text{m}$
2. B double the distance of the object
3. C half the distance of the object
4. D equal to the distance of the object in front of it

A concave lens is

1. A of the same thickness at every point
2. B thicker in the middle and thinner at the edges
3. C thinner in the middle and thicker at the edges
4. D always thicker at one edge than at the other

A convex mirror can never form an image on a screen because the image it forms is

1. A always coloured differently from the object
2. B always inverted
3. C always virtual
4. D always exactly the same size as the object

A convex lens gives a virtual, erect and enlarged image when the object is placed

1. A behind the screen
2. B very close to the lens
3. C exactly where the screen stands
4. D very far from the lens