JCECE Medical JCECE Medical Solved Paper-2014

  • question_answer
    A charge q coulomb makes n revolutions in one second in a circular orbit of radius r. The magnetic field at the centre of the orbit in \[N{{A}^{-1}}{{m}^{-1}}\]

    A)  \[\frac{2\pi rn}{q}\times {{10}^{-7}}\]

    B)  \[\left( \frac{2\pi q}{r} \right)\times {{10}^{-7}}\]

    C)  \[\left( \frac{2\pi q}{nr} \right)\times {{10}^{-7}}\]

    D)  \[\left( \frac{2\pi nq}{r} \right)\times {{10}^{-7}}\]

    Correct Answer: D

    Solution :

     Magnetic field at the centre \[B=\frac{{{\mu }_{0}}nl}{2r}\] \[B=\frac{2{{\mu }_{0}}nl}{4r\pi }\times \pi \] \[B=\frac{2{{\mu }_{0}}n/\pi }{4\pi r}\] \[B=\frac{2\pi nl}{r}\times {{10}^{-7}}\] \[\left[ \because \,\frac{{{\mu }_{0}}}{4\pi }={{10}^{-7}} \right]\] \[B=\left( \frac{2\pi nq}{r} \right)\times {{10}^{-7}}\] \[[\because \,q=lt]\]


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