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

  • question_answer
    A circular coil is radius 5 cm has 500 turns of a wire. The approximate value of the coefficient of self-induction of the coil will be-

    A) \[25\text{ }mH\]

    B) \[25\times {{10}^{-3}}\,mH\]

    C) \[50\times {{10}^{-3}}\,mH\]

    D) \[50\times {{10}^{-3}}\,H\]

    Correct Answer: A

    Solution :

    [a] \[\phi =Li\Rightarrow NBA=Li\] Since magnetic field at the centre of circular coil carrying current is given by \[B=\frac{{{\mu }_{0}}}{4\pi }\],  \[\frac{2\pi Ni}{r}\] \[\therefore \,\,\,\,N.\frac{{{\mu }_{0}}}{4\pi }\,\,.\frac{2\pi Ni}{r}.\,\,\pi {{r}^{2}}=Li\Rightarrow L=\frac{{{\mu }_{0}}{{N}^{2}}\pi r}{2}\] Hence self-inductance of a coil \[\frac{4\pi \times {{10}^{-7}}\times 500\times 500\times \pi \times 0.05}{2}=25mH\]


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