CBSE notes-Light
CBSE notes-Light Define 1 dioptre of power of a lens. Power of lens is defined as the reciprocal of its focal length. If P is the power of a lens of focal length F in metres, then P=1/f The S.I. unit of power of a lens is Dioptre. It is denoted by D. 1 dioptre is defined as the power of a lens of focal length 1 metre. ∴1 D = 1 m−1