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

  • question_answer
    A copper rod of length 0.19 m is moving parallel to a long wire with a uniform velocity of 10 m/s. The long wire carries 5 ampere current and is perpendicular to the rod. The ends of the rod are at distances 0.01 m and 0.2 m from the wire. The emf induced in the rod will be-

    A) \[10\,\mu V\]

    B) \[20\,\mu V\]

    C) \[30\,\mu V\]     

    D) \[40\,\mu V\]

    Correct Answer: C

    Solution :

    [c] EMF induced in an element of length dx at a distance x from wire =\[Bvdx\] \[\therefore \]   Total EMF induced in the rod \[E=\int\limits_{0.01}^{0.2}{Bv}\,\,dx=\int\limits_{0.01}^{0.2}{\frac{{{\mu }_{0}}iv}{2\pi x}}\]  \[dx=\frac{{{\mu }_{0}}iv}{2\pi }\,\,\]  \[\int\limits_{0.01}^{0.2}{\frac{1}{x}}\,dx\] \[E=\frac{{{\mu }_{0}}iv}{2\pi }\left[ {{\log }_{e}}x \right]_{0.01}^{0.2}=\frac{{{\mu }_{0}}iv}{2\pi }[{{\log }_{10}}(0.2)-{{\log }_{10}}\] \[(0.01)]\times 2.303\] \[E=\frac{4\pi \times {{10}^{-7}}\times 5\times 10}{2\pi }[1.301]\times 2.303\] \[=2.99\times {{10}^{-5}}\,V\approx 30\mu V\]


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