JEE Main & Advanced Physics Magnetic Effects of Current / करंट का चुंबकीय प्रभाव Question Bank Biot-savart's Law and Amperes Law

  • question_answer
    A long wire carries a steady current. It is bent into a circle of one turn and the magnetic field at the centre of the coil is B. It is then bent into a circular loop of n turns. The magnetic field at the centre of the coil will be              [AIEEE 2004]

    A)            nB

    B)            n2B

    C)            2nB                                          

    D)            2n2B

    Correct Answer: B

    Solution :

                       Magnetic field at the center of single turn loop  \[B=\frac{{{\mu }_{0}}}{4\pi }.\frac{2\pi i}{r}\], magnetic field at the center of n-turn loop             \[{{B}_{n}}=\left( \frac{{{\mu }_{0}}}{4\pi }.\frac{2\pi i}{r/n} \right)\times n\Rightarrow {{B}_{n}}={{n}^{2}}B\]


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