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NEET Physics Electro Magnetic Induction NEET PYQ-Electro Magnetic Induction

  • question_answer
    A coil of resistance \[400\,\Omega \] is placed in a magnetic field. If the magnetic flux \[\phi \] (Wb) linked with the coil varies with time t (sec) as \[\phi =50\,{{t}^{2}}+4\]. The current in the coil at \[t=2s\] is               [AIPMT (S) 2012]

    A)  0.5 A

    B)                   0.1 A

    C)  2 A                 

    D)       1 A

    Correct Answer: A

    Solution :

    Induced emf of coil \[E={{\left| -\frac{d\phi }{dt} \right|}_{t}}\]
    Given, \[\phi =50{{t}^{2}}+4\] and \[R=400\,\Omega \]
    \[E={{\left| -\frac{d\phi }{dt} \right|}_{t=2}}\]
    \[=|100t{{|}_{t=2}}=200\,V\]
    Current in the coil
                \[i=\frac{E}{R}=\frac{200}{400}\]
                            \[=\frac{1}{2}=0.5A\]


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