Question

A doctor has prescribed a corrective lens of power +1.5 D to a patient. Find the focal length of the lens in centimeter. Is the prescribed lens diverging or converging?

Answer 1

Given,

Power, $P=1.5D$

focal length in metres, $f=\frac{1}{P}$

$f=\frac{1}{1.5}m$

$f=\frac{2}{3}m$

$=\frac{2}{3}\times 100$

$f=66.7cm$

The power is positive, lens is convex i.e., converging