Question

size of an image of an object by a mirror (f=20cm) is reduced *by* 1/3 of its height. At what distance has the object been placed from the mirror? Find the nature of the image.​

Answer 1

Answer:

Correct option is

A

80 cm

Using magnification formula,

m=−

u

v

=

3

1

⇒v=−

3

u

From mirror formula,

v

1

+

u

1

=

f

1

From above two equations,

−u

3

+

−u

1

=

20

1

u=−80 cm

So, the object is placed at a distance of 80cm in front of the mirror.