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A non-conducting ring having q uniformly...

A non-conducting ring having q uniformly distributed over its circumference is placed on a rough horizontal surface. A vertical time varying magnetic field `B = 4t^(2)` is switched on at time t = 0. Mass of the ring is m and radius is R.
The ring starts rotating after 2 s, the coefficient of friction between the ring and the table is

A

`(4qmR)/g`

B

`(2qmR)/g`

C

`(8qR)/(mg)`

D

`(qR)/(2mg)`

Text Solution

Verified by Experts

The correct Answer is:
C
`ointE.dl=-(d phi)/(dt) rArr Exx2piR=piR^(2)(dB)/(dt) rArr E=R/2xx8t=R8 rArr (qE)R=(mumg)R rArr mu=(8qR)/(mg)`
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