Manipal Medical Manipal Medical Solved Paper-2011

  • question_answer
    Light of frequency\[v\]is incident on a substance of threshold frequency\[{{v}_{0}}({{v}_{0}}<v)\]. The energy of the emitted photoelectron will be

    A)  \[h(v-{{v}_{0}})\]

    B)  \[h/v\]

    C)  \[he(v-{{v}_{0}})\]

    D)  \[h/{{v}_{0}}\]

    Correct Answer: A

    Solution :

     Einstein explained the phenomenon of photo- electric effect on the basis of Plancks theory. According to which the kinetic energy of photoelectrons emitted from the metal surface is E and\[\phi \]is the work function of the metal, then \[E=hv-\phi \]                 ...(i) where\[hv\]is the energy of the photon absorbed by the electron in the metal. If for a given metal, the threshold frequency of light be\[{{v}_{0}}\] then an amount of energy\[h{{v}_{0}}\]of the photon of light will be spent in ejecting the electron out of the metal. ie,              \[\phi =h{{v}_{0}}\]                 ...(ii) From Eqs. (i) and (ii), we get \[E=hv-h{{v}_{0}}\] \[\Rightarrow \] \[E=h(v-{{v}_{0}})\]


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