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Haryana PMT Haryana PMT Solved Paper-2002

  • question_answer
    A wire of length \[L\] carries a current \[I.\] it is                 bent in the form of a circle. The magnetic             moment of current loop (in amp-m ) is :

    A) \[\frac{I{{L}^{2}}}{4{{\pi }^{2}}}\]                                             

    B) \[I\pi {{L}^{2}}\]

    C) \[\frac{I{{L}^{2}}}{4\pi }\]                                            

    D) \[4\pi I{{L}^{2}}\]

    Correct Answer: C

    Solution :

                    Magnetic moment  \[M=IA\] Length of wire is L \[\therefore \]  \[2\pi r=L\]                 \[r=\frac{L}{2\pi }\] \[\therefore \]  \[M=I\,\pi {{r}^{2}}\]                 \[=I\frac{\pi {{L}^{2}}}{4{{\pi }^{2}}}\]                 \[=\frac{I{{L}^{2}}}{4\pi }\]


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