CET Karnataka Engineering CET - Karnataka Engineering Solved Paper-2010

  • question_answer
    Magnetic field at the centre of a circular coil of radius R due to \[i\] flowing through it is B. The magnetic field at a point along the axis at distance R from the centre is

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

    B) \[\frac{B}{4}\]

    C) \[\frac{B}{\sqrt{8}}\]                     

    D) \[\sqrt{8}B\]

    Correct Answer: C

    Solution :

    The magnetic field at a point along the axis at distance R from the centre of a circular coil of radius R carrying current \[i\] is                 \[{{B}_{A}}=\frac{{{\mu }_{0}}2\pi i{{R}^{2}}}{4\pi {{({{R}^{2}}+{{R}^{2}})}^{3/2}}}\]                 \[=\frac{{{\mu }_{0}}i}{2\sqrt{8}R}\]                 \[=\frac{B}{\sqrt{8}}\]                   \[\left[ {{B}_{centre}}=B=\frac{{{\mu }_{0}}i}{2R} \right]\]


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