RAJASTHAN ­ PET Rajasthan PET Solved Paper-2007

  • question_answer
    The inductance of a coil is L = 10 H and resistance R = 5\[\Omega \]. If applied voltage of battery is 10 V and it switches off in 1 millisecond, find induced emf of inductor.

    A)  \[2\times {{10}^{4}}V\]        

    B)  \[1.2\times {{10}^{4}}V\]

    C)  \[2\times {{10}^{-4}}V\]        

    D)  None of these

    Correct Answer: A

    Solution :

     Amount of magnetic flux linked with inductor is \[\phi =Li\] Now, the emf induced in the inductor is given by \[e=-\frac{d\phi }{dt}=\frac{d}{dt}(Li)\] Or \[e=-L\frac{di}{dt}\] \[|e|=-L\frac{di}{dt}\] Here, induced current\[=\frac{V}{R}=\frac{10}{5}\] \[=2A\] Circuit switches off in millisecond or        \[dt=1\times {{10}^{3}}s\] and         \[L=10H\] \[\therefore \] Induced emf in inductor is \[|e|=10\times \frac{2}{1\times {{10}^{-3}}}\] \[|e|=2\times {{10}^{4}}V\]


You need to login to perform this action.
You will be redirected in 3 sec spinner