AMU Medical AMU Solved Paper-2011

  • question_answer
    An electron having momentum \[2.4\times {{10}^{-23}}\text{ }kg-m/s\]enters a region of uniform magnetic field of 0.15 T. The field vector makes an angle of 30° with the initial velocity vector of the electron. The radius of the helical path of the electron in the field shall be

    A)  \[2\,m\,m\]                                      

    B)  \[1\,m\,m\]

    C)   \[\frac{\sqrt{3}}{2}m\,m\]                        

    D)  \[0.5\,m\,m\]

    Correct Answer: D

    Solution :

                                     Radius of the helical path of the electron in the field                 \[r=\frac{mv\sin \theta }{qB}\]                 \[r=\frac{2.4\times {{10}^{-23}}\sin {{30}^{o}}}{1.6\times {{10}^{-19}}\times 0.15}\]         \[=\frac{2.4\times {{10}^{-23}}\times \frac{1}{2}}{1.6\times {{10}^{-19}}\times 0.15}\]                                                 \[=5\times {{10}^{-4}}m=0.5\,\,mm\]


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