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NEET AIPMT SOLVED PAPER SCREENING 2012

  • 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 = 2 s is

    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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