CET Karnataka Engineering CET - Karnataka Engineering Solved Paper-2008

  • question_answer
    The resultant force on the current loop PQRS due to a long current carrying conductor will be

    A)                  \[{{10}^{-4}}N\]                              

    B)                  \[3.6\times {{10}^{-4}}N\]

    C)  \[1.8\times {{10}^{-4}}N\]                          

    D)  \[5\times {{10}^{-4}}N\]

    Correct Answer: D

    Solution :

    Force on SR and PQ are equal but opposite so their net will be zero. Force between two parallel conductors carrying currents \[{{I}_{1}}\] and \[{{I}_{2}}\]                 \[F=\frac{{{\mu }_{0}}}{2\pi }\frac{{{I}_{1}}{{I}_{2}}l}{r}\] where r = distance between two parallel                                                           conductors                 \[{{F}_{PS}}=\frac{{{10}^{-7}}\times 2\times 20\times 20\times 15\times {{10}^{-2}}}{2\times {{10}^{-2}}}\]                 \[=6\times {{10}^{-4}}N\]                 \[{{F}_{QR}}=\frac{{{10}^{-7}}\times 2\times 20\times 20\times 15\times {{10}^{-2}}}{12\times {{10}^{-2}}}\]                 \[=1\times {{10}^{-4}}N\]                 \[{{F}_{net}}={{F}_{PS}}-{{F}_{QR}}\]                 \[=6\times {{10}^{-4}}-1\times {{10}^{-4}}=5\times {{10}^{-4}}N\]


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