A thin converging lens has a power of 4.0 diopters determined its focal length.

A. 2.50m
B. 0.03m
C. 5.00m
D. 0.25m

Correct Answer:

Option D – 0.25m

Explanation

The power of a lens is defined as the reciprocal of the focal length ,expressed in metre.Mathematically, the power of a lens in dioptres is given by:(100)/f(in cm).
thus for lens of power of 4.0 dioptres we have that: (100)/(f) = +4.0
f= (100)/(4.0) = 25cm
= 0.25cm