JEE Main & Advanced Physics Magnetic Effects of Current / करंट का चुंबकीय प्रभाव Question Bank Biot-savart's Law and Amperes Law

  • question_answer
    In the figure shown there are two semicircles of radii \[{{r}_{1}}\] and \[{{r}_{2}}\] in which a current i is flowing. The magnetic induction  at the centre O will be

    A)            \[\frac{{{\mu }_{0}}i}{r}({{r}_{1}}+{{r}_{2}})\]

    B)            \[\frac{{{\mu }_{0}}i}{4}({{r}_{1}}-{{r}_{2}})\]

    C)            \[\frac{{{\mu }_{0}}i}{4}\left( \frac{{{r}_{1}}+{{r}_{2}}}{{{r}_{1}}{{r}_{2}}} \right)\]

    D)            \[\frac{{{\mu }_{0}}i}{4}\left( \frac{{{r}_{2}}-{{r}_{1}}}{{{r}_{1}}{{r}_{2}}} \right)\]

    Correct Answer: C

    Solution :

                       The magnetic induction due to both semicircular parts will be in the same direction perpendicular to the paper inwards.            \[\therefore B={{B}_{1}}+{{B}_{2}}=\frac{{{\mu }_{0}}i}{4{{r}_{1}}}+\frac{{{\mu }_{0}}i}{4{{r}_{2}}}=\frac{{{\mu }_{0}}i}{4}\left( \frac{{{r}_{1}}+{{r}_{2}}}{{{r}_{1}}{{r}_{2}}} \right)\otimes \]


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