Question

an object of size 4 cm is placed in front of a concave lens of focal length 20cm at a distance twice the focal length .Calculate image distance and its magnification

Answer 1

Dear Student

h = 4 cm
f = - 20 cm
u = 40 cm

According to Lens Maker Formula
1/f = 1/v - 1/u
1/-20 = 1/v - 1/40
v = - 40 cm

m = v/u = -40/40 = -1

The image is of same size as that of object.

Regards