Question

define one dioptre power of a lense​

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.

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Answer 2

One diaptre is the power of a lens of focal length one metre