Question

define the power of lens and its unit​

Answer 1

The power of a lens is defined as the reciprocal of its focal length in meters, or D = 1/f, where D is the power in diopters and f is the focal length in meters. Lens surfacepower can be found with the index of refraction and radius of curvature

The SI unit of power is dioptre.

or

The power of a lens is the reciprocal of its focal length, more technically, its second principal focal length. In S.I. its unit is dioptre which is equal to per meter. So we can say that if focal length of a lens is 2 m, its power is 0.5 dioptre

Answer 2

Answer:

power of lens is known as the inverse of the focal length of the lens measuring in meter

SI power = dioptre (D)

power of lens = 1/focal length of meter