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A horizontal ring of radius r = (1)/(2) ...

A horizontal ring of radius `r = (1)/(2) m` is kept in a vertical constant magentic field `1 T`. The ring is collapsed from maximum area to zero area in `1 s`. Then the emf induced in the ring is

A

`1 V`

B

`(pi//4) V`

C

`(pi//2) V`

D

`pi V`

Text Solution

Verified by Experts

The correct Answer is:
B
`|e| = B (dA)/(dt)`
`|e| = B ((A_(2) - A_(1)))/((t_(2) - t_(1))`
`|e| = (1((pi)/(4) - 0))/((1 - 0))`
`e = (pi)/(4) V`
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