question_answer

A convex lens forms an image at a distance 10 cm when a parallel beam of light is incident on it. Find the position (s) of a concave mirror of radius of curvature 5 cm such that the final image is formed at infinity

A)  at a distance 10 cm from the lens.

B)  at a distance of 15 cm from the lens.

C)  at a distance of 5 cm from the lens.

D)  both [a] and [b].

Correct Answer: D

Solution :

Ray diagram for option A Ray diagram for Option B In the first ray diagram point O is the pole of the mirror and in the second ray diagram point C is the center of curvature of the mirror. It follows from the principle of reversibility of light that the final image in both the cases will be formed at infinity. Hence, the correction option is [d].