Question

A beam of light travelling to the principal axis of a concave lens appears to diverge from a point 20 CM behind the lens after passing through the lens... find the power of the lens???​
​

Answer 1

Answer:

-5D

Explanation:

The point where the rays diverge in concave lens is called focal point

given,

        f=20cm

        p=100/f  (when f is in cm)

        therefore,

                        p=100/20

                          = 5

        therefore ,

                        p = -5D ( For concave lens , power is negative )