Question

What is meant by power of lens ?writ SI unit .A student uses a lens of focal length 40cm and another of 20cm . write the nature and power of each lens

Answer 1

The power of the lens is the reciprocal of its focal lens. Its s.i unit is diaoptre.

Formula D=1/F

A studeng uses a lens of focal lenth 40cm andanother 20cm

D=1/40. And another is D=1/20

If the power of the lens is positive so it is a convex lens and nehative so it is a concave lens

.in theabove case the student using a convex lens because the power D

Is positive

Answer 2

p=1/f

unit is diopter