JEE Main & Advanced Physics Electro Magnetic Induction Question Bank Self Evaluation Test - Electromagnetic Induction

  • question_answer
    PQ is an infinite current carrying conductor. AB and CD are smooth conducting rods on which a conductor EF moves with constant velocity v as shown. The force needed to maintain constant speed of EF is        

    A) \[\frac{1}{vR}{{\left[ \frac{{{\mu }_{0}}Iv}{2\pi }In\,\left( \frac{b}{a} \right) \right]}^{2}}\]

    B) \[{{\left[ \frac{{{\mu }_{0}}Iv}{2\pi }In\left( \frac{a}{b} \right) \right]}^{2}}\frac{1}{vR}\]

    C) \[{{\left[ \frac{{{\mu }_{0}}Iv}{2\pi }In\left( \frac{b}{a} \right) \right]}^{2}}\frac{v}{R}\]

    D) \[\frac{v}{R}{{\left[ \frac{{{\mu }_{0}}Iv}{2\pi }In\left( \frac{a}{b} \right) \right]}^{2}}\]

    Correct Answer: A

    Solution :

    [a] Induced emf \[=\int\limits_{a}^{b}{Bvdx=\int\limits_{a}^{b}{\frac{{{\mu }_{0}}I}{2\pi x}vdx}}\] \[\Rightarrow \,\,Induced\,emf=\frac{{{\mu }_{0}}Iv}{2\pi }In\left( \frac{b}{a} \right)\] \[\Rightarrow \,\] Power dissipated \[=\frac{{{E}^{2}}}{R}\] Also, power=\[F.v\Rightarrow F=\frac{{{E}^{2}}}{vR}\] \[\Rightarrow \,\,F=\frac{1}{vR}{{\left[ \frac{{{\mu }_{0}}Iv}{2\pi }In\left( \frac{b}{a} \right) \right]}^{2}}\]


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