Question

An image, three times as large as the object is produced by a spherical mirror .If the focal length of the mirror is 30cm then the distance of the object from the pole of the spherical mirror will be

Answer 1

Answer:

Correct option is

B

15cm

Given, u=−20cm

m=−3⇒

u

−v

=−3

v=−60cm

f

1

=

v

1

+

u

1

=

60

−1

−

20

1

=

60

−1−3

f=

4

−60

=−15cm

i.e., focal length should be 15cm