Question

When a fork is seen through lenses A and B one by one, it appears as shown in the diagrams. What is the nature of

1. lens A, and
2. lens B?

Give reason for your answer.

Answer 1

1. When the fork is seen through lens A, it appears to be diminished. Such a diminished image is observed when it is placed near a concave lens. Therefore, lens A is concave, i.e., diverging in nature.
2. When the fork is seen through lens B, it appears to be enlarged. Such an enlarged image is formed by a convex lens when an object is placed between the lens and its focus. Therefore, lens B is a convex, i.e., converging lens in nature.