BVP Medical BVP Medical Solved Paper-2002

  • question_answer
    The maximum velocity of an electron emitted by light of wavelength X incident on the surface of a metal of work function \[\theta \], is :

    A)  \[{{\left[ \frac{2(h\lambda -\theta )}{m} \right]}^{{1}/{2}\;}}\] 

    B) \[{{\left[ \frac{2(hc-\lambda \phi )}{m\lambda } \right]}^{{1}/{2}\;}}\]

    C)  \[\left[ \frac{2(hc-\lambda \phi )}{m} \right]\]                 

    D) \[{{\left[ \frac{2(hc-\lambda \phi )}{m\lambda } \right]}^{{1}/{2}\;}}\]

    Correct Answer: B

    Solution :

                    From Einsteins photo electric equation. Energy of photon \[=\phi +\frac{1}{2}m{{\upsilon }^{2}}\] \[\frac{hc}{\lambda }=\phi +\frac{1}{2}m{{\upsilon }^{2}}\] \[\frac{1}{2}m{{\upsilon }^{2}}=\left( \frac{hc}{\lambda }=\phi  \right)\] \[{{\upsilon }^{2}}=2\left( \frac{hc-\lambda \phi }{m\lambda } \right)\] \[\upsilon ={{\left[ \frac{2(hc-\lambda \phi )}{m\lambda } \right]}^{1/2}}\]


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