Chhattisgarh PMT Chhattisgarh PMT Solved Paper-2007

  • question_answer
    An electron of 100 eV energy is projected towards large negatively charged plate having charge density \[-2\times 10{{-}^{6}}C/{{m}^{2}}.\] Then, what must be the distance of electron, so it does not strike the plate?

    A)  0.44mm                              

    B)  0.44cm

    C)  044m                                   

    D)  None of these

    Correct Answer: A

    Solution :

    Let the distance of electron from the negatively charged plate be 5, then Kinetic energy of electron =work done by electron                 \[KE=F\times s\]                 \[=Eq\times s\]                 \[K=\frac{\sigma }{{{\varepsilon }_{0}}}\times q\times s\] \[\therefore \]  \[s=\frac{K{{\varepsilon }_{0}}}{\sigma q}\]                 \[=\frac{100\times 1.6\times {{10}^{-19}}\times 8.85\times {{10}^{-12}}}{2\times {{10}^{-6}}\times 1.6\times {{10}^{-19}}}\]                 \[=50\times 8.85\times {{10}^{-6}}\]                 \[=442.50\times {{10}^{-6}}m\]                 \[=0.44\times {{10}^{-3}}m\]                 \[=0.44mm\]


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