When a person with a near point at 28 cm uses a certain magnifying glass,it produces an angular magnification of 7.0 with the image very distant.What is the focal length of the lens of this magnifying glass?
A)2.0 cm
B)3.0 cm
C)4.0 cm
D)5.0 cm
E)6.0 cm

Question

Quizplus · Accepted Answer

The angular magnification (M) is given by M = 1 + (D/f), where D is the near point distance (28 cm) and f is the focal length. For a distant image, M = D/f. Solving 7 = 28/f gives f = 4 cm.

When a Person with a near Point at 28 Cm