An object is placed at a distance of 60 cm from a converging lens with a focal length of 20cm. What is the magnification of the lens?

Answer 1

(I shall use the Cartesian Sign Convention)

Object distance = u = - 60cm
Focal length = f = + 20cm (The focal length of a converging lens is taken as positive)

Image distance = v

As per the lens formula,
(1/v) = (1/u) + (1/f)
(1/v) = (1/20) - (1/60)
v = 30 cm

Magnification = -(v/u)
= 30/60
= 0.5

Answer 2

Why do object distance consider as negative