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A circular coil of radius 10 cm, 500 tur...

A circular coil of radius 10 cm, 500 turns and resistance `2 Omega` is placed with its plane, perpendicular to the horizontal component of the earth's magnetic field. It is rotated about its vertical diameter through `180^(@)` in 0.25 s. The induced emf in the coil is (take `H_(E)=3.0xx10^(-5)T`)

A

`6.6xx10^(-4)V`

B

`1.4xx10^(-2)V`

C

`2.6xx10^(-2)V`

D

`3.8xx10^(-3)V`

Text Solution

Verified by Experts

The correct Answer is:
D
`A=pixx10^(2)=3.14xx10^(2)cm^(2)=3.14xx10^(-2)m^(2)`
Considering the surroundings as vacuum or air,
`B=3.0xx10^(-5)T,N=500`
Initially, magnetic flux linked with the coil,
`phi_(1)=NBA`
By rotating the coil through `180^(@)`, magnetic flux linked with the coil, `phi_(2)=-NBA`
`therefore` Induced emf,
`e=-(Deltaphi)/(Deltat)=-(phi_(2)-phi_(1))/(Deltat)=(2NBA)/(Deltat)`
`=(2xx500xx(3xx10^(-5))xx(3.14xx10^(-2)))/(0.25)`
`~~3.8xx10^(-3)V`
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