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An object is placed in front of a mirror...

An object is placed in front of a mirror at a distance of `60cm`. If its two times diminished image is formed on the screen, the focal length of the mirror is

A

`20cm`

B

`45cm`

C

`15cm`

D

`90cm`

Text Solution

Verified by Experts

The correct Answer is:
A
`M=(-v)/(u)=(-1)/(2)impliesv=(u)/(2)=-30cm`
`(1)/(f)=(1)/(v)+(1)/(u)impliesf=-20cm`
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