Question

An object of height 4 cm forms a real image of height 12 cm when placed at a distance of 20 cm forms a concave mirror if the image formed is real then find the focal length of the mirror​

Answer 1

Answer:

Magnification m=

u

−v

−4=

−20

−v

v=−80cm

From mirror formula

v

1

+

u

1

=

f

1

−80

1

+

−20

1

=

f

1

f

1

=

−80

1+4

f=−16cm

Thus focal length of converging mirror is 16 cm.