Question

A card sheet divided into squares each of size 1 mm2 is being viewed at a distance of 9 cm through a magnifying glass (a converging lens of focal length 9 cm) held close to the eye. (a) What is the magnification produced by the lens? How much is the area of each square in the virtual image? (b) What is the angular magnification (magnifying power) of the lens? (c) Is the magnification in (a) equal to the magnifying power in (b)? Explain.

Answer 1

In Concave lens ,

1/v + 1/u = 1/f

u =9cm

f = 9 cm

v = ?

1/v = - 1/9 - 1/9

1/v = -2/9 , v = 9/2 = 4.5cm

Therefore,

m = v/u

m = 9/2 / 9

m = 9/2 * 1/9

m = 1/2