Question

What is the meaning of saying '' the power of lens is 1 dioptre''

Answer 1

1 dioptre is SI unit of the power of a lens whose focal length is 1 metre. It is denoted by the letter D. Thus 1D = 1 m-1. Simply, when focal length ‘ f ‘ is expressed in metres, then, power is expressed in dioptres. The power of a convex lens is positive and that of a concave lens is negative.

Answer 2

$1dioptre \: is \: power \: of \: lens \: \\ whose \: focal \: length \: is \: 1cm \: \\ \\ 1d= \frac{1}{1m}$

$hope \: my \: answer \: helps \: you$