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A conducting loop of radius R is present...

A conducting loop of radius R is present in a uniform magnetic field B perpendicular to the plane of the ring. If radius R varies as a function of time t, as `R =R_(0) +t`. The emf induced in the loop is

A

`2pi(R_(0)+t)B` clockwise

B

`pi(R_(0)+t)B` clockwise

C

`2pi(R_(0)+t)B` anticlockwise

D

zero

Text Solution

Verified by Experts

The correct Answer is:
C
Given`R=(R_0)+t`
`A=pi R^(2)=pi(R_(0)+t)^(2), (dA)/(dt) = 2 pi (R_(0)+t)`
therefore, emf induced in the loop is
`e=B(dA)/(dt) = 2 pi (R_(0)+t)B`
Since area is increasing, induced emf is in anticlockwise sense to oppose the chang in flux.
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