RAJASTHAN ­ PET Rajasthan PET Solved Paper-2010

  • question_answer
    Current i is carried in a wire of length L. If the wire  is turned into a circular coil, the maximum magnitude of torque in a given magnetic field B will be

    A)  \[\frac{Li{{B}^{2}}}{2}\]                  

    B)  \[\frac{L{{i}^{2}}B}{2}\]

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

    D)  \[\frac{L{{i}^{2}}B}{4\pi }\]

    Correct Answer: D

    Solution :

     \[{{\tau }_{\max }}=NiAB=1\times i\times (\pi {{r}^{2}})\times B\] \[\left( 2\pi r=L\Rightarrow r=\frac{L}{2\pi } \right)\] \[{{\tau }_{\max }}=\pi i{{\left( \frac{L}{2\pi } \right)}^{2}}B\] \[{{\tau }_{\max }}=\frac{{{L}^{2}}iB}{4\pi }\]


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