CET Karnataka Engineering CET - Karnataka Engineering Solved Paper-2007

  • question_answer
    A charged particle is moving in a magnetic field of strength B perpendicular to the direction of the field. If q and m denote the charge and mass of the particle respectively, then the frequency of rotation of the particle is

    A)  \[f=\frac{qB}{2\,\pi m}\]                            

    B)  \[f=\frac{qB}{2\,\pi {{m}^{2}}}\]

    C)  \[f=\frac{2\,{{\pi }^{2}}m}{qB}\]                             

    D)  \[f=\frac{2\,\pi \,m}{qB}\]

    Correct Answer: A

    Solution :

    Lorentz force = centripetal force \[i.e.,\] \[Bq\,v=\frac{m{{v}^{2}}}{r}\] \[\Rightarrow \]               \[B\,q=m\,\omega \] \[\Rightarrow \]               \[B\,\,q=m2\pi f\]           (as \[v=r\,\omega \]) \[\therefore \]  \[f=\frac{B\,q}{2\pi m}\]


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