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

  • question_answer
    Which one of the following is not correct about Lorentz force?

    A) In presence of electric field \[\overrightarrow{E}(r)\] and magnetic field \[\overrightarrow{B}(r)\]the force on a moving electric charge is \[\overrightarrow{F}=q[\overrightarrow{E}(r)+\overrightarrow{v}\times \overrightarrow{B}(r)]\].

    B) The force, due to magnetic field on a negative charge is opposite to that on a positive charge.

    C) The force due to magnetic field becomes zero if velocity and magnetic field are parallel or anti-parallel

    D) For a static charge the magnetic force is maximum.

    Correct Answer: D

    Solution :

    (d) For a static charge the magnetic force is maximum. If charge is not moving then the magnetic force is zero. Since \[{{\overrightarrow{F}}_{m}}=q(\overrightarrow{v}\times \overrightarrow{B})\] As \[\overrightarrow{v}=0\], for stationary charge \[\therefore {{\overrightarrow{F}}_{m}}=0\]


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