12th Class Physics Magnetism Question Bank MCQ - Moving Charges and Magnetism

  • question_answer
    A tightly wound 90 turn coil of radius 15 cm has a magnetic field of \[4\times {{10}^{-4}}T\] at its centre. The current flowing through it is:

    A) 1.06 A                          

    B) 2.44 A

    C) 3.44 A                          

    D) 4.44 A

    Correct Answer: A

    Solution :

    (a) 1.06 A Here,                 \[N=90\] \[R=15\,cm=15\times {{10}^{-2}}m,\,B=4\times {{10}^{-4}}T\] \[\because B=\frac{{{\mu }_{0}}Nl}{2R}\] \[\therefore \,\,\,\,\,\,\,\,l=\frac{2RB}{N{{\mu }_{0}}}=\frac{2\times 15\times {{10}^{-2}}\times 4\times {{10}^{-4}}}{4\pi \times {{10}^{-7}}\times 90}=1.06A\]


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