Question

. A concave mirror forms virtual image at a distance of 30 cm from mirror if object is placed at a distance of 15 cm from it. Find the focal length of the concave mirror.

Answer 1

Answer:

Answer

A.

u=−30cm,m=−3,

m=

f−u

f

⇒−3=

f−(−30)

f

=

f+30

f

⇒−3f−90=f

⇒−4f=90

→f=−

4

90

=−

2

45

=−22.5cm