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

  • question_answer
    When radiation is incident on a photoelectron emitter, the stopping potential is found to be 9 volts. If \[e/m\] for the electron is \[1.8\times {{10}^{11}}\,C\,k{{g}^{-1}}\] the maximum velocity of the ejected electrons is                      [Kerala (Engg.) 2002]

    A)            \[6\times {{10}^{5}}\,m{{s}^{-1}}\]                                

    B)            \[8\times {{10}^{5}}\,m{{s}^{-1}}\]

    C)            \[1.8\times {{10}^{6}}\,m{{s}^{-1}}\]                            

    D)            \[1.8\times {{10}^{5}}\,m{{s}^{-1}}\]

    Correct Answer: C

    Solution :

               \[\frac{1}{2}mv_{\max }^{2}=e{{V}_{0}}\Rightarrow {{v}_{\max }}=\sqrt{2\left( \frac{e}{m} \right){{V}_{0}}}\] \[=\sqrt{2\times 1.8\times {{10}^{11}}\times 9}=1.8\times {{10}^{6}}m/s.\]


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