Question

Assertion (A): A piece of paper is placed on the ground in bright sunshine and a converging lens is held at some distance above the piece of paper in such a way that a sharp image of the sun is formed on the piece of paper. After a few minutes, the paper burns at the point of image and a hole is formed in it.

Reason (R): The converging lens concentrates a lot of sun’s rays to a small point on paper (called focus). The heat energy of these concentrated sun rays burns the paper to form a hole in it.

Options

• Both A and R are true and R is correct explanation of the assertion.

• Both A and R are true but R is not the correct explanation of the assertion.

• A is true but R is false.

• A is false but R is true.

Answer 1

Both A and R are true and R is correct explanation of the assertion.

Explanation:

The assertion is true because a convex lens acts as a converging lens that can focus parallel sunlight into a tiny, sharp spot. The reason is also true and correctly explains the event, as concentrating the parallel solar rays at the principal focus creates an intense buildup of heat energy that elevates the temperature of the paper until it burns.