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A conducting circular loop is placed in ...

A conducting circular loop is placed in a uniform magnetic field, `B=0.025T` with its plane perpendicular to the loop. The radius of the loop is made to shrink at a constant rate of `1 mms^(-1)`. The induced emf when the radius is `2 cm` is

A

`(pi)/(2)muV`

B

`2 mu V`

C

`2 (pi)/(mu V)`

D

`(pi)/(mu V)`

Text Solution

Verified by Experts

The correct Answer is:
D
Loop is placed in magnetic field B = 0.025 T
`(dr)/(dt)= 1 xx 10^(-3) m//s`
`phi= BA= Bpir^(2)`
emf of cell for `r= 2 xx 10^(-2)`
`epsilon|_(r= 2 xx 10^(-2))= (dphi)/(dt)= Bpi2r(dr)/(dt)`
`epsilon= 0.025 pi xx 2 xx 10^(-3) xx 1 xx 10^(-2)`
`(25)/(1000)pi xx 2 xx 2 xx 10^(-5)V= pi xx 10^(-6)V`
`epsilon= pi mu V`
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