JEE Main & Advanced Physics Magnetic Effects of Current / करंट का चुंबकीय प्रभाव Question Bank Self Evaluation Test - Moving Charges and Mangetism

  • question_answer
    The magnetic field due to a current carrying circular loop of radius 3 cm at a point on the axis at a distance of 4 cm from the centre is \[54\,\mu T\]. What will be its value at the centre of loop?              

    A) \[125\mu T\]

    B) \[150\mu T\]

    C) \[250\mu T\]

    D) \[75\mu T\]

    Correct Answer: C

    Solution :

    [c] \[B=\frac{{{\mu }_{0}}i\,\,{{a}^{2}}}{1{{({{x}^{2}}+{{a}^{2}})}^{3/2}}}\] \[B'=\frac{{{\mu }_{0}}i}{2a}=\frac{{{\mu }_{0}}i\,{{a}^{2}}}{2a{{({{x}^{2}}+{{a}^{2}})}^{3/2}}}\left( \frac{{{({{x}^{2}}+{{a}^{2}})}^{3/2}}}{{{a}^{2}}} \right)\] \[B'=\frac{B.{{({{x}^{2}}+{{a}^{2}})}^{3/2}}}{{{a}^{3}}}\] Put \[x=4\And a=3\Rightarrow B'=\frac{54({{5}^{3}})}{3\times 3\times 3}=250\mu T\]


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