A lens has a refractive power of −1.50 D. What is its focal length?
A) 150 cm
B) −150 cm
C) 66.7 cm
D) −66.7 cm
E) 8.50 cm

Name: A lens has a refractive power of −1.50 D. What is its focal length? A) 150 cm B) −150 cm C) 66.7 cm D) −66.7 cm E) 8.50 cm
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Question

Quizplus · Accepted Answer

The focal length $f$ in meters is given by the reciprocal of the lens power in diopters (D), so $f = \frac{1}{-1.50} = -0.666...$ meters, which is -66.7 cm.

A Lens Has a Refractive Power of −1