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A uniform but time-varying magnetic fiel...

A uniform but time-varying magnetic field B(t) exists in a circular region of radius a and is directed into the plane of the paper, as shown. The magnitude of the induced electric field at point P at a distance r from the centre of the circular region

A

is zero

B

decreases as `1//r`

C

increases as `r`

D

decreases as `1//r^(2)`

Text Solution

Verified by Experts

The correct Answer is:
B
`E(2pi r) = pia^(2) (dB)/(dt)` for `r gt = a`
`rArr E = (a^(2))/(2r) (dB)/(dt) rArr E prop (1)/(r )`
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