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Haryana PMT Haryana PMT Solved Paper-2005

  • question_answer
    A wire of length \[L\] metre carrying a current \[I\] ampere is bent in the form of a circle. The magnitude of its magnetic moment is :

    A) \[IL/4\pi \]                                         

    B)  \[{{I}^{2}}{{L}^{2/}}4\pi \]

    C)  \[{{I}^{2}}L/8\pi \]                         

    D)  \[I{{L}^{2}}/8\pi \]

    Correct Answer: A

    Solution :

                    If r is the radius of circle then \[L=2\pi r\] or            \[r=\frac{L}{2\pi }\] \[\therefore \]  Area \[=\pi {{r}^{2}}=\pi {{L}^{2}}/4{{\pi }^{2}}\]                 \[=\frac{{{L}^{2}}}{4\pi }\] Now magnetic moment                 \[M=NiA=I{{L}^{2}}/4\pi \]


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