A magnifying glass uses a converging lens with a refractive power of 20 diopters.What is the angular magnification if the image is to be viewed by a relaxed eye with a near point of 25 cm?
A)5.0
B)3.0
C)4.0
D)1.0
E)2.0

Question

Quizplus · Accepted Answer

The angular magnification (M) of a magnifying glass is given by M = 1 + (D/f), where D is the near point distance (25 cm or 0.25 m) and f is the focal length of the lens. The refractive power (P) is 20 diopters, so f = 1/P = 1/20 = 0.05 m. Thus, M = 1 + (0.25/0.05) = 1 + 5 = 6. However, the relaxed eye condition typically uses M = D/f, which gives M = 0.25/0.05 = 5.0.

A Magnifying Glass Uses a Converging Lens with a Refractive