EAMCET Medical EAMCET Medical Solved Paper-2008

  • question_answer
    A circular coil of wire of radius r has N turns and carries a current I. The magnetic induction  at a point on the axis of the coil at a distance \[\sqrt{3}\]r from its centre is

    A)  \[\frac{{{\mu }_{0}}IN}{4r}\]                                     

    B)  \[\frac{{{\mu }_{0}}IN}{8r}\]

    C)   \[\frac{{{\mu }_{0}}IN}{16\pi r}\]                           

    D)  \[\frac{{{\mu }_{0}}IN}{32r}\]

    Correct Answer: C

    Solution :

                     The magnetic induction at any point distance \[x\]from its centre \[B=\frac{{{\mu }_{0}}}{4\pi }.\frac{2\pi NI{{r}^{2}}}{{{({{r}^{2}}+{{x}^{2}})}^{3/2}}}\]                                      ?(i) where r is the radius of the circular coil. Then, \[B=\frac{{{\mu }_{0}}}{4\pi }\frac{2\pi NI{{r}^{2}}}{{{[{{r}^{2}}+{{(\sqrt{3}r)}^{2}}]}^{3/2}}}\]                 or \[B=\frac{{{\mu }_{0}}}{2\pi }.\frac{NI{{r}^{2}}}{{{({{r}^{2}}+3{{r}^{2}})}^{3/2}}}\]        [Given, \[x=\sqrt{3r}\]] or            \[B=\frac{{{\mu }_{0}}}{2\pi }.\frac{NI{{r}^{2}}}{{{(4{{r}^{2}})}^{3/2}}}\] or            \[B=\frac{{{\mu }_{0}}}{2\pi }.\frac{NI{{r}^{2}}}{{{(2r)}^{3}}}\] or            \[B=\frac{{{\mu }_{0}}}{2\pi }.\frac{NI{{r}^{2}}}{8{{r}^{3}}}\] or            \[B=\frac{{{\mu }_{0}}NI}{16\pi r}\]


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