JEE Main & Advanced Physics Magnetic Effects of Current / करंट का चुंबकीय प्रभाव Question Bank Motion of Charged Particle In Magnetic Field

  • question_answer
    An electron having charge \[1.6\times {{10}^{-19}}\,C\] and mass \[9\times {{10}^{-31}}\,kg\] is moving with \[4\times {{10}^{6}}\,m{{s}^{-1}}\] speed in a magnetic field \[2\times {{10}^{-1}}\,tesla\] in a circular orbit. The force acting on electron and the radius of the circular orbit will be [MP PET 1996; JIPMER 2000; BVP 2003]

    A)            \[12.8\times {{10}^{-13}}N,\,1.1\times {{10}^{-4}}m\]

    B)            \[1.28\times {{10}^{-14}}N,\,1.1\times {{10}^{-3}}m\]

    C)            \[1.28\times {{10}^{-13}}N,\,1.1\times {{10}^{-3}}m\]

    D)            \[1.28\times {{10}^{-13}}N,\,1.1\times {{10}^{-4}}m\]

    Correct Answer: D

    Solution :

                       F = evB\[=1.6\times {{10}^{-19}}\times 4\times {{10}^{6}}\times 2\times {{10}^{-1}}\]\[=1.28\times {{10}^{-13}}N\] Also \[\frac{m{{v}^{2}}}{r}=evB\Rightarrow r=\frac{mv}{eB}\]            \[\Rightarrow \ r=\frac{9\times {{10}^{-31}}\times 4\times {{10}^{6}}}{1.6\times {{10}^{-19}}\times 2\times {{10}^{-1}}}=1.1\times {{10}^{-4}}m\]


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