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

  • question_answer
    The magnetic moment of a current carrying loop is \[2.1\times {{10}^{-25}}\,amp\times {{m}^{2}}\]. The magnetic field at a point on its axis at a distance of \[1\,{AA}\] is

    A) \[4.2\times {{10}^{-2}}\,weber/{{m}^{2}}\]               

    B) \[4.2\times {{10}^{-3}}\,weber/{{m}^{2}}\]

    C) \[4.2\times {{10}^{-4}}\,weber/{{m}^{2}}\]               

    D) \[4.2\times {{10}^{-5}}\,weber/{{m}^{2}}\]

    Correct Answer: A

    Solution :

    Field at a point \[x\]from the centre of a current carrying loop on the axis is                    \[\text{B}=\frac{{{\mu }_{\text{0}}}}{4\pi }.\frac{2M}{{{x}^{3}}}=\frac{{{10}^{-7}}\times 2\times 2.1\times {{10}^{-25}}}{{{({{10}^{-10}})}^{3}}}\]            \[\]\[=4.2\times {{10}^{-32}}\times {{10}^{30}}=4.2\times {{10}^{-2}}W/{{m}^{2}}\]


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