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Q6.3   A long solenoid with 15 turns per cm has a small loop of area 2.0 cm^{2} placed inside the solenoid normal to its axis. If the current carried by the solenoid changes steadily from 2.0 A to 4.0 A  in 0.1s, what is the induced emf in the loop while the current is changing?

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Given in a solenoid,

The number of turns per unit length is:

  n = 15turn/cm=1500turn/m 

loop area :

 A=2cm^2=2*10^{-4}m

Current in the solenoid :

initial current = I_{initial}=2

finalcurrent = I_{final}=4

change in current :

 \Delta I= 4-2 = 2

change in time:

\Delta t=0.1s

Now, the induced emf:

e=\frac{d\phi }{dt}=\frac{d(BA)}{dt}=\frac{d(\mu _0nIA)}{dt} = \mu _0nA\frac{dI}{dt}=\mu _0nA\frac{\Delta I}{\Delta t}

 

e=4\pi*10^{-7}*1500*2*10^{-4}*\frac{2}{0.1}=7.54*10^{-6}

Hence, the induced emf in the loop is 7.54*10^{-6}.

Posted by

Pankaj Sanodiya

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