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

  • question_answer
    A charged particle is moving on circular path with velocity v in a uniform magnetic field B, if the velocity of the charged particle is doubled and strength of magnetic field is halved, then radius becomes:

    A) 8 times                         

    B) 4 times

    C) 2 times                         

    D) 16 times      

    Correct Answer: B

    Solution :

    (b) 4 times.                                          As         \[Bqv==\frac{m{{v}^{2}}}{r}\] or      \[r=\frac{mv}{Bq}\] According to the question, \[v'=2v\] and \[B'=\frac{B}{2}\] \[\therefore r'\frac{mv'}{B'q}=\frac{m(2v)}{(B/2)q}=\frac{4mv}{Bq}=4r\]


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