NEET Sample Paper NEET Sample Test Paper-9

  • question_answer If the maximum kinetic energy, of emitted photoelectron from a metal surface of work function \[2.5\text{ }eV\] is\[1.7\text{ }eV\]. If wavelength of incident radiation is halved, then stopping potential will be:

    A)  \[2.5\,V\]                    

    B)  \[5.9\,V\]

    C)  \[5\,V\]                       

    D)  \[1.1\,V\]

    Correct Answer: B

    Solution :

    As energy associated with the photon is given by: \[\frac{hc}{\lambda }=h\upsilon \] \[=2.5+1.7=4.2eV\] and           \[\upsilon \lambda =c\] Now,         \[V'\frac{\lambda }{2}=c\] \[\Rightarrow \]               \[V'=2V\] \[\Rightarrow \]               \[e{{V}_{0}}=h\,(2V)-\phi \]                 \[=2\times 4.2-2.5\]                 \[{{V}_{0}}=5.9V\]

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