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JEE Main & Advanced Physics Electro Magnetic Induction Question Bank Critical Thinking

  • question_answer
    A wire of length 1 m is moving at a speed of 2ms?1 perpendicular to its length and a homogeneous magnetic field of 0.5 T. The ends of the wire are joined to a circuit of resistance 6 W. The rate at which work is being done to keep the wire moving at constant speed is    [Roorkee 1999]

    A)            \[\frac{1}{12}W\]               

    B)            \[\frac{1}{6}W\]

    C)            \[\frac{1}{3}W\]                 

    D)            1W

    Correct Answer: B

    Solution :

                       Rate of work \[=\frac{W}{t}=P=Fv;\] also \[F=Bil=B\,\left( \frac{Bvl}{R} \right)\ l\] Þ \[P=\frac{{{B}^{2}}{{v}^{2}}{{l}^{2}}}{R}=\frac{{{(0.5)}^{2}}\times {{(2)}^{2}}\times {{(1)}^{2}}}{6}=\frac{1}{6}W\]


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