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JEE Main & Advanced Sample Paper JEE Main - Mock Test - 45

  • question_answer
    ABCD is a wire frame in the shape of an isosceles trapezium (i.e., length AR = length CD) enter a magnetic field with flux density B at \[t=0\]as shown in the figure. If the total resistance of wire frame is R, what is the value of the induced current in the wire frame after t seconds, assuming that the frame has not entered the field completely by then?

    A) zero                  

    B)        \[\frac{Bv}{R}(2vt\,\,\sin \theta +\ell )\]

    C) \[\frac{Bv}{R}\left( \frac{2vt}{\tan \theta }+\ell  \right)\]

    D)        \[\frac{B}{v}\]

    Correct Answer: C

    Solution :

    [c] Total effective length crossing the flux lines \[=\frac{2vt}{\tan \theta }+\ell \] Current \[=\frac{B\left( \frac{2vt}{\tan \theta }+\ell  \right)v}{R}\]


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