NEET Sample Paper NEET Sample Test Paper-72

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

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

    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 and inwards. \[B={{B}_{1}}+{{B}_{2}}=\frac{{{\mu }_{0}}i}{4{{r}_{1}}}+\frac{{{\mu }_{0}}i}{4{{r}_{2}}}+\frac{{{\mu }_{0}}i}{4}\left( \frac{{{r}_{1}}+{{r}_{2}}}{{{r}_{1}}{{r}_{2}}} \right)\otimes \]


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