Question

The power of lens is 2.1 D. What is its focal length ?​

Answer 1

Answer:

p=1/f

=> f=1/p

=1/2.1

=0.47m

Answer 2

Answer:

Solution :

Power of lens = -2.0 Dioptre

Let the focal length of the lens be f.

We know that

1

Power of lens = focal length

-2.0 -2 f

= -0.5 metre %3D

Since the focal length of the lens is negative. So, it is a concave lens.

[I hope help]