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A convex lens is placed in contact with ...

A convex lens is placed in contact with a plane mirror. A point object at a distance of 20 cm on the axis of this combination has its image coincding with itself. What is the focal length of the lens?

A

20cm

B

45cm

C

60cm

D

30cm

Text Solution

Verified by Experts

The correct Answer is:
D
`3/(2V_(1))=1/(6R)to(2)`
from (1) and (2)
`R=30cm`
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