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NEET Sample Paper NEET Sample Test Paper-28

  • question_answer
    A wire of length 'L' is shaped into a circle and then bent about its one of the diameter in such a way that the two semi circles becomes perpendicular to each other. If i current flows through the loop then magnetic moment of system is :-

    A)  \[\frac{\sqrt{2}i{{L}^{2}}}{8\pi }\]      

    B)  \[\sqrt{3}\frac{i{{L}^{2}}}{4\pi }\]

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

    D)  \[\frac{i{{L}^{2}}}{2\pi }\]

    Correct Answer: A

    Solution :

    Magnetic moment of circular loop: \[M=iA=i(\pi {{R}^{2}}).\] where \[L=2\pi R\] \[=\frac{i{{L}^{2}}}{4\pi }\]                     ?..(i) Magnetic moment of each semicircle             \[M'=\frac{iA}{2}=\frac{i{{L}^{2}}}{8\pi }\]       ........(ii) [From (i)] Magnetic moment of system :-             \[{{M}_{net}}=\sqrt{{{M}^{'2}}+{{M}^{'2}}}\] \[=\sqrt{2}M'=\sqrt{2}\frac{i{{L}^{2}}}{8\pi }\]   [From(ii)]       


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