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A candle is placed 20cm from the surface...

A candle is placed 20cm from the surface of a convex mirror and a plane mirror is also placed so that the virtual images in the two mirrors coincide. If the plane mirror is 12 cm away from the object, what is the focal length of the convex mirror?

A

5 cm

B

10 cm

C

20 cm

D

40 cm

Text Solution

Verified by Experts

The correct Answer is:
A
For a plane mirror
Object distance = Image distance
`:.` For convex mirror v=24-20=4cm
u = 20cm then `1/f=1/v-1/u`
(Apply necessary sign convention)
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