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

  • question_answer
    The magnetic force per unit length on a wire carrying a current of 10 A and making an angle of \[45{}^\circ \] with the direction of a uniform magnetic field of 0.20 T is:

    A) \[2\sqrt{2}N{{m}^{-1}}\]                     

    B) \[\frac{2}{\sqrt{2}}N{{m}^{-1}}\]

    C) \[\frac{\sqrt{2}}{2}N{{m}^{-1}}\]                   

    D) \[4\sqrt{2}N{{m}^{-1}}\]

    Correct Answer: B

    Solution :

    (b) \[\frac{2}{\sqrt{2}}N{{m}^{-1}}\]                         \[I=10\,A,\,\theta =45{}^\circ ,B=0.2\,T\]             \[\therefore F=lIB\,\sin \theta \]             \[\therefore \frac{F}{l}=IB\,\sin \,45{}^\circ =10\times 0.2\times \frac{1}{\sqrt{2}}=\frac{2}{\sqrt{2}}N{{m}^{-1}}\]


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