MGIMS WARDHA MGIMS WARDHA Solved Paper-2015

  • question_answer
    The magnetic moment of a short bar magnet is \[4\text{ }A{{m}^{2}}\]The magnetic induction at a point 10 cm away from its mid point on axial line is\[{{B}_{1}}\]and on the equatorial line is\[{{B}_{2}}\]then

    A)  \[{{B}_{1}}=8\times {{10}^{-4}}T,{{B}_{2}}=4\times {{10}^{-4}}T\]

    B)  \[{{B}_{1}}=2\times {{10}^{-4}}T,{{B}_{2}}=1\times {{10}^{-4}}T\]

    C)  \[{{B}_{1}}=10\times {{10}^{-4}}T,{{B}_{2}}=5\times {{10}^{-4}}T\]

    D)  \[{{B}_{1}}=6\times {{10}^{-4}}T,{{B}_{2}}=3\times {{10}^{-4}}T\]

    Correct Answer: A

    Solution :

                    Given \[d=10\text{ }cm=0.1m\]                             \[\frac{{{\mu }_{0}}}{4\pi }={{10}^{-7}}T{{A}^{-1}}\]                 \[{{B}_{axial}}=\frac{{{\mu }_{0}}}{4\pi }\times \frac{2\mu }{{{d}^{3}}}\]                 \[={{10}^{-7}}\times \frac{2\times 4}{{{(0.1)}^{3}}}=8\times {{10}^{-4}}T\]                 \[{{B}_{equitorial}}=\frac{{{\mu }_{0}}}{4\pi }\times \frac{\mu }{{{d}^{3}}}=4\times {{10}^{-4}}T\]


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