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JEE Main & Advanced Sample Paper JEE Main Sample Paper-7

  • question_answer
    A triangular loop of equal sides of length \[\ell \] carries a current. The loop is kept in a magnetic field B, directed parallel to one side PQ (as shown). The torque on the loop is

    A)  zero                                     

    B)  \[\sqrt{3}i\ell B\]

    C)  \[3i{{\ell }^{2}}B\]                          

    D)  \[\frac{\sqrt{3}}{4}i{{\ell }^{2}}B\]

    Correct Answer: D

    Solution :

    Magnetic moment \[=M=IA=i\frac{\sqrt{3}{{\ell }^{2}}}{4}\] Since \[\vec{A}\bot \vec{B},\] we have Torque \[=\tau =MB\,\sin \,{{90}^{o}}\] \[=\sqrt{3}\frac{i{{\ell }^{2}}B}{4}\]


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