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) 2.0
E) 1.0

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 (in meters) and f is the focal length of the lens (also in meters). The refractive power (P) of the lens is given by P = 1/f (in diopters), so f = 1/P. Given P = 20 diopters, f = 1/20 meters = 0.05 meters. With D = 25 cm = 0.25 meters, M = 1 + (0.25/0.05) = 1 + 5 = 6. However, since the options provided do not include 6, and considering the standard formula for angular magnification for a relaxed eye is M = D/f (assuming the initial explanation had an oversight in adding 1), we recalculate: M = 0.25/0.05 = 5. Therefore, the correct choice is A) 5.0, acknowledging a clarification in the explanation process.

A Magnifying Glass Uses a Converging Lens with a Refractive