Define I dioptre of newer of a lefts Ans. 1 dioptre is the power of a lens whose focal length is 1 metre.
1 dioptre of lens power is defined as the unit of measurement of a lens's or curved mirror's optical power equal to the reciprocal of focal length ( f ). P = 1 f = 1 D. The focal length is measured in metres. The SI unit of lens power is dioptre, which has a focal length of one metre and is denoted by the letter D .
