Question

A converging mirror focus a real image of
height 4 cm of object of height 1 cm placed 20 cm away from the mirror .calculate the
distance. What is the focal length of the mirror.

Answer 1

Dear Student,

Given that

Height of object, h = 1 cm

Height of image, h^/ = -4 cm

Object distance, u = -20 cm

Now,

Magnification, m = -v/u = h^//h

=> v/20 = -4/1

=> v = -80 cm

This is the image distance.

Now,

1/f = 1/v + 1/u

=> 1/f = -1/80 – 1/20

=> f = -16 cm

This is the focal length of the mirror.

Regards