Question

A person with defective eyesight is unable to see objects clearly nearer than 1.5 m. He wants to read a book placed at a distance of 30 cm from his eyes. The type of a required lens and its focal length is

• A. Concave lens, f = 37.5 cm
• B. Convex lens, f = 30.5 cm
• C. Convex lens, f = 37.5 cm
• D. Concave lens, f = 30.5 cm

Answer 1

The correct option is C

Convex lens, f = 37.5 cm

The person is hypermetropic. This defect is corrected by using a convex lens of appropriate power.

u = -30 cm and v = - 1.5 m = -150 cm

Lens formula:

f = + 37.5 cm, convex lens