A lens with a focal length of 20 cm has what power?
A)5.0 diopters
B)0.2 diopters
C)2 diopters
D)-5.0 diopters
E)0.02 diopters

Question

A lens with a focal length of 20 cm has what power?
A)5.0 diopters
B)0.2 diopters
C)2 diopters
D)-5.0 diopters
E)0.02​ diopters

Quizplus · Accepted Answer

The power of a lens is given by the formula $P = \frac{1}{f}$, where $P$ is the power in diopters and $f$ is the focal length in meters. Since the focal length given is 20 cm, we first convert it to meters: 20 cm = 0.2 m. Thus, $P = \frac{1}{0.2} = 5.0$ diopters.

A Lens with a Focal Length of 20 Cm Has