Question

What is meant by power of a lens ?​

Answer 1

Answer:

Power of lens is the ability of the lens to converge the rays of light falling on it. It can also be defined as P=1/f where f is the focal length. S.I. unit of power is D(Dioptre).

Answer 2

The power of a lens may be defined as the reciprocal of its focal length in metres. The power of lens is inversely proportional to its focal length, hence the lens of short focal length has more power and the lens of long focal length has less power.

The SI unit of power of lens is dioptre. It is denoted by D. One dioptre is the power of a lens whose focal length is 1 m. A convex lens has a positive focal length, hence it's power is also positive. A concave lens has a negative focal length, hence it's power is also negative.

P = 1/f