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VIT Engineering VIT Engineering Solved Paper-2010

  • question_answer
      The maximum velocity of electrons emitted from a metal surface is\[v\], when frequency of light falling on it is\[f\]. The maximum velocity when frequency becomes \[4f\]is

    A)  \[2v\]

    B)  \[>2v\]

    C)  \[<2v\]

    D)  between \[2v\] and \[4v\]  

    Correct Answer: B

    Solution :

    \[\because \]  \[E={{W}_{0}}+\frac{1}{2}mv_{\max }^{2}\] \[\Rightarrow \] \[{{v}_{\max }}=\sqrt{\frac{2(hf-{{W}_{0}})}{m}}\] If frequency becomes 4f then \[v=\sqrt{\frac{2(h\times 4f-{{W}_{0}})}{m}}=2\sqrt{\frac{2\left( hf-\frac{{{W}_{0}}}{4} \right)}{m}}\] \[\Rightarrow \] \[v>2v\]


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