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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 isA. `96xx10^-21N`B. `48x10^-21N`C. `24xx10^-21N`D. zero |
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Answer» Correct Answer - 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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