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

Correct Answer: Option D

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