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A uniform but time varying magnetic fiel...

A uniform but time varying magnetic field `B=(2t^3+24t)T` is present in a cylindrical region of radius `R =2.5` cm as shown in figure.

The force on an electron at `P` at `t=2.0` s is

A

`96xx10^-21N`

B

`48x10^-21N`

C

`24xx10^-21N`

D

zero

Text Solution

Verified by Experts

The correct Answer is:
B
`(dB)/(dt)=(6t^2+24)T//s`
At `t=2s, (dB)/(dt)=48T//s`
`El=(dphi)/(dt)=S((dB)/(dt))`
or `E(2pir)=pir^2((dB)/(dt))`
` :. E=r/2.(dB)/(dt)` ...(i)
`F=qE=(qr)/2 (dB)/(dt)`
`=((1.6xx10^-19)(1.25xx10^-2))/2(48)`
`=48xx10^-21N`
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