JEE Main & Advanced Physics Magnetic Effects of Current / करंट का चुंबकीय प्रभाव Question Bank Self Evaluation Test - Moving Charges and Mangetism

  • question_answer
                An alternating electric field, of frequency v, is applied across the dees (radius=R) of a cyclotron that is being used to accelerate protons (mass=m). The operating magnetic field used in the cyclotron and the kinetic energy (K) of the proton beam, produced by it, are given by:

    A) \[B=\frac{mv}{e}\]and \[K=2m{{\pi }^{2}}{{v}^{2}}{{R}^{2}}\]

    B) \[B=\frac{2\pi mv}{e}\] and \[K={{m}^{2}}\pi v{{R}^{2}}\]

    C) \[B=\frac{2\pi mv}{e}\] and \[K=2m{{\pi }^{2}}{{v}^{2}}{{R}^{2}}\]

    D) \[B=\frac{mv}{e}\] and \[K={{m}^{2}}\pi v{{R}^{2}}\]

    Correct Answer: C

    Solution :

    [c] Time period of cyclotron is \[T=\frac{1}{v}=\frac{2\pi m}{eB}\]; \[B=\frac{2\pi m}{e}v\]; \[R=\frac{mv}{eB}=\frac{P}{eB}\] \[\Rightarrow \,\,\,P=eBR=e\times \frac{2\pi mv}{e}R=2\pi mvR\] \[K.E.=\frac{{{P}^{2}}}{2m}=\frac{{{(2\pi mvR)}^{2}}}{2m}2{{\pi }^{2}}m{{v}^{2}}{{R}^{2}}\]


You need to login to perform this action.
You will be redirected in 3 sec spinner