AMU Medical AMU Solved Paper-2001

  • question_answer
    Light of two different frequency whose photon have energies 1 eV and 2.5 eV  respectively successively illuminate a metal of work function 0.5 eV. The ratio of maximum speed of the emitted electron will be

    A)  1 : 1                                      

    B)  1 : 2

    C)  1 : 4                                      

    D)  1 : 5

    Correct Answer: B

    Solution :

                     From Einsteins photoelectric equation, we get                                 \[{{E}_{k}}=hv-W\] In first case                 \[\frac{1}{2}m{{v}^{2}}=1\,eV-0.5\,eV=0.5\,eV\]              ... (i) In second case                 \[\frac{1}{2}mv_{1}^{2}=2.5\,eV-0.5\,eV=2\,eV\]            ... (ii) Dividing Eqs. (ii) by (i), we get                 \[\frac{v_{1}^{2}}{{{v}^{2}}}=\frac{2}{0.5}=4\] \[\Rightarrow \]               \[\frac{{{v}_{1}}}{v}=\frac{2}{1}\] \[\Rightarrow \]               \[\frac{v}{{{v}_{1}}}=\frac{1}{2}\]


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