Question

Assertion (A): In order to read small letters found in a dictionary conveniently, we should use a diverging lens of short focal length.

Reason (R): A converging lens has a focal length of 0.5x. In order to obtain an image which is real, inverted and same size as the object, the object should be placed at a distance x in front of 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

A is false but R is true.

Explanation:

The assertion is false because we should use a converging (convex) lens of short focal length, not a diverging lens, to read small letters as a magnifying glass. The reason is true because if the focal length f is 0.5x, the centre of curvature 2f is at a distance x, which is precisely where an object must be placed to form a real, inverted, and same-sized image.