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A small plane mirror placed at the centr...

A small plane mirror placed at the centre of a spherical screen of radius R. A beam of light is falling on the mirror, If the mirror makes `n` revolution per second, the speed of light on the screen after reflection from the mirror will be

A

`4 pi n R `

B

`2 pi n R `

C

`(nR )/(2pi )`

D

`( nR )/( 4 pi)`

Text Solution

Verified by Experts

The correct Answer is:
A
When plane mirror rotates through an angle `theta` , the reflected ray rotates by an angle `2 theta`.
Hence, spot on the screen will make 2n revolution per second. i.e. (2`pi` R)2n = 4`pi` n R.
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