Question

define 1 dioptre of power of a lens????

Answer 1

1 Dioptre is the power of a lens whose focal length is 1 metre.

Because ,

$Power = \frac{1}{f}$

where, f is the focal length in metres.

Answer 2

 Dioptre is the power of a lens whose focal length is 1 metre.

Because ,

Power = \frac{1}{ f}Power=f1​

where, f is the focal length in metres.