Question

What is the power of a concave lens of focal length 200 cm?

Answer 1

Since p= 1/f (in meters)

So,P= 1 /F= 100/200=1/2= 0 .5

(Now,the lens used is concave so the power would be negative .)

hence p= -0.5

Answer 2

Answer:

The power of the concave lens is -0.5 D

Explanation:

Given That,

focal length f = 200 cm

We know that,

The power of the lens is the reciprocal of the focal length of the lens.

$P = \dfrac{1}{f}$

The power of the concave lens is

$P = \dfrac{100}{200}$

$P = 0.5\ D$

We know that,

The focal length is the negative for the concave lens.

Therefore,

The power of the concave lens is

$P = -0.5 D$

Hence, The power of the concave lens is -0.5 D.