Question

define power of lens and state its unit

Answer 1

power of a lens is the converging or diverging power of the lens it's S.I. unit is dioptre

Answer 2

Power of lens is the ability of the lens to converge the rays of light falling on it.
Definition : The power of lens is the reciprocal of its focal length in meters. It is represented by the letter P. The power P of lens of focal length f is given by f = 1/P. The SI unit of power is dioptre.