VIT Engineering VIT Engineering Solved Paper-2011

  • question_answer
    Light of two different frequencies whose photons have energies 1 eV and 2.5 eV, respectively, successively illuminate a metal whose work function is 0,5 eV. The ratio of the maximum speed of the emitted electrons will be

    A)  1 : 5          

    B)  1 : 4

    C)  1 : 2          

    D)  1 : 1

    Correct Answer: C

    Solution :

    If E is the energy of incident photon and \[{{W}_{0}}\] the work function, then \[E-{{W}_{0}}=\] available energy \[E-{{W}_{0}}=\frac{1}{2}m{{v}^{2}}\] \[v=\sqrt{\frac{2(E-{{W}_{0}})}{m}}\] \[\frac{{{v}_{1}}}{{{v}_{2}}}=\sqrt{\frac{1-0.5}{2.5-0.5}}\] \[=\sqrt{\frac{0.5}{2}}=\frac{1}{2}\]


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