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Behind a thin converging lens having bot...

Behind a thin converging lens having both the surfaces of the same radius 10cm, a plane mirror has been placed. The image of an object at a distance of 40 cm from the lens is formed at the same position. What is the refractive index of the lens?

A

`1.5`

B

`5//3`

C

`9//8`

D

None of these

Text Solution

Verified by Experts

The correct Answer is:
c.
"O" act as the focal point.
Also, `(1)/(f)=(mu-1)((1)/R_(1)-(1)/R_(2))`
`rArr (1)/(40)=(mu-1)((1)/(10)+(1)/(10))`
`(1)/(40)=(mu-1)((2)/(10))`
`rArr mu=9//8`
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