Question

A student uses a lens of focal length 40 cm and another of –20 cm. Write the nature and power of each lens

Answer 1

Power of first lens, `P_1 = 1/(f(m)) = 1/0.4 = 2.5 D`

The given lens is a converging lens i.e. a convex lens.

Power of second lens, `P_2 = 1/f(m)` = `-1/0.2` = -5D

The given lens is a diverging lens i.e. a concave lens.