BVP Medical BVP Medical Solved Paper-2007

  • question_answer
    If the work function of a photometal is 6.875eV, its threshold wavelength will be \[(Take\text{ }c=3\times {{10}^{8}}m/s)\]

    A)                  3600\[\mu =0.3\]                           

    B)                  2400 \[\therefore \]

    C)                  1800\[F=0.3\times 250=75N.\]                 

    D)                  1200 \[\overrightarrow{\mathbf{F}}\]

    Correct Answer: C

    Solution :

                    The minimum energy required for the emission of photoelectron from a metal is called work function of that metal, \[W=\frac{hc}{\lambda }\] where h is Plancks constant, c is speed of light, \[\lambda \] is wavelength. \[\Rightarrow \]               \[\lambda =\frac{hc}{W}\]                 \[=\frac{6.6\times {{10}^{-34}}\times 3\times {{10}^{8}}}{6.825\times 1.6\times {{10}^{-19}}}\]                 \[=1.8\times {{10}^{-7}}\]                 \[=1800\times {{10}^{-10}}m\]                 \[=1800\overset{\text{o}}{\mathop{\text{A}}}\,\]


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