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KVPY Sample Paper KVPY Stream-SX Model Paper-17

  • question_answer
    One of the two identical conducing wires of length L is bent in the form of a circular loop and the other one into a circular coil' of N identical turns. If the same current is passed in both, the ratio of the magnetic field at the central of the loop \[({{B}_{L}})\]to that at the centre of the coil \[({{B}_{C}}),\,ie.\frac{\text{BL}}{\text{BC}}\]will be:

    A) N

    B) \[\frac{1}{\text{N}}\]

    C) \[{{\text{N}}^{2}}\]

    D) \[\frac{1}{{{\text{N}}^{2}}}\]

    Correct Answer: D

    Solution :

    \[{{B}_{L}}=\frac{{{\mu }_{0}}i}{2R}\] \[{{B}_{C}}=\frac{{{\mu }_{0}}Ni}{2(R/N)}\] \[\therefore \]      \[\frac{{{B}_{L}}}{{{B}_{C}}}=\frac{1}{{{N}^{2}}}.\]


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