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

  • question_answer
    The radius of the orbital of electron in the hydrogen atom 0.5 Å. The speed of the electron is \[2\times {{10}^{6}}m/s\]. Then the current in the loop due to the motion of the electron is [RPMT 1996]

    A)            1 mA                                        

    B)            1.5 mA

    C)            2.5 mA                                    

    D)            \[1.5\times {{10}^{-2}}mA\]

    Correct Answer: A

    Solution :

                       Time period of revolution of electron \[T=\frac{2\pi }{\omega }=\frac{2\pi r}{v}\]                    Hence corresponding electric current \[i=\frac{e}{T}=\frac{ev}{2\pi r}\]            \[\Rightarrow \,\,i=\frac{1.6\times {{10}^{-19}}\times 2\times {{10}^{6}}}{2\times 3.14\times 0.5\times {{10}^{-10}}}=1\,mA.\]


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