Question

A person having a myopic eye uses a concave lens of focal length 50cm. what is the power of the lense?

Answer 1

So  focal length = - 50 cm = - 0.50 meter

power = - 1/0.50 = -2 Dioptre or - 2 D

Answer 2

Explanation:

focal length = - 50 cm = - 0.50 meter

power = - 1/0.50 = -2 Dioptre or - 2 D

Hence the power of the lens is -2D