CET Karnataka Medical CET - Karnataka Medical Solved Paper-2013

  • question_answer
    Maximum velocity of the photoelectron emitted by a metal is \[1.8\times {{10}^{6}}m{{s}^{-1}}\]. Take the value of specific charge of the electron is \[1.8\times {{10}^{11}}C\,k{{g}^{-1}}\]. Then the stopping potential in volt is

    A)  \[1\]     

    B)  \[3\]     

    C)  \[9\]     

    D)  \[6\]

    Correct Answer: C

    Solution :

    : As  \[\frac{1}{2}m\upsilon _{\max }^{2}=e{{V}_{S}}\] where \[{{\upsilon }_{\max }}\]is  the maximum velocity of the electron and \[{{V}_{S}}\] is the stopping potential. \[{{V}_{S}}=\frac{1}{2}\frac{m}{e}\upsilon _{\max }^{2}\] Here, \[\frac{e}{m}=1.8\times {{10}^{11}}C\,k{{g}^{-1}},\,{{\upsilon }_{\max }}=1.8\times {{10}^{6}}m{{s}^{-1}}\] \[\therefore \] \[{{V}_{S}}=\frac{1}{2}\times \frac{1}{1.8\times {{10}^{11}}}\times {{(1.8\times {{10}^{6}})}^{2}}=9V\]


You need to login to perform this action.
You will be redirected in 3 sec spinner