Question

Define one dioptre of a power of a lens.

Answer 1

Hi.....

Here is your answer...


1 dioptre is SI unit of the power of a lens whose focal length is 1metre. Simply, when focal length ' f ' is expressed in metres, then,power is expressed in dioptres.

Hope this helps you.....

Please mark as the brainliest answer......

Answer 2

“A dioptre is a unit of measurement of the optical power of a lens or curved mirror, which is equal to the reciprocal of the focal length measured in metres (that is, 1/metres).

It is thus a unit of reciprocal length.

For example, a 3-dioptre lens brings parallel rays of light to focus at  1⁄3 metre. A flat window has an optical power of zero dioptres, and does not converge or diverge light.”

As the focal length is given in mm, the optical power is measured in units of 1/mm

Converting the optical power to units of 1/m results in “diopters”.

A lens of 4 diopters has a optical power of 4/m = 4/1m = 4/1000mm

Its focal length is 1000mm/4 = 250mm

Correspondingly a lens of f= 100mm has an optical power of

1/f= 1/100mm= 10/1m = 10 diopters