JEE Main & Advanced Physics Photo Electric Effect, X- Rays & Matter Waves Question Bank Cathode Rays and Positive Rays

  • question_answer
    When electron beam passes through an electric field, they gain kinetic energy. If the same beam passes through magnetic field, then

    A)            Their energy increases

    B)            Their momentum increases

    C)            Their potential energy increases

    D)            Energy and momentum both remains unchanged

    Correct Answer: D

    Solution :

               Because magnetic force always points perpendicular to the particle velocity. That is why velocity remains unchanged thereby keeping energy \[\left( \frac{1}{2}m{{v}^{2}} \right)\] and momentum (mv) unchanged.


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