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JCECE Engineering JCECE Engineering Solved Paper-2009

  • question_answer
    A solenoid \[1.5\,\,m\] long and \[0.4\,\,cm\] in diameter possesses \[10\] turns per \[cm\] length. A current of \[5\,\,A\] falls through it. The magnetic field at the axis inside the solenoid is

    A) \[2\pi \times {{10}^{-3}}T\]                         

    B) \[2\pi \times {{10}^{-5}}T\]

    C) \[4\pi \times {{10}^{-2}}T\]                         

    D) \[4\pi \times {{10}^{-3}}T\]

    Correct Answer: A

    Solution :

    Magnetic field at the axis inside the solenoid                 \[B={{\mu }_{0}}ni\] Here,\[n=10\,\,turns/cm=1000\,\,turns/m,\,\,i=5A\] \[\therefore \]  \[B=4\pi \times {{10}^{-7}}\times 1000\times 5\]                     \[=2\pi \times {{10}^{-3}}T\]


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