2. Solved Papers
  3. Manipal Medical

Manipal Medical Manipal Medical Solved Paper-2006

  • question_answer
    Silver has a work function of 4.7 eV. When ultraviolet light of wavelength 100 nm is incident upon it, a potential of 7.7 V is required to stop the photoelectrons from reaching the collector late. How mcuh potential will be required to stop photoelectrons when light of wavelength 2p0 nm is incident upon silver?

    A)  1.5V           

    B)  3.85V

    C)  2.35V          

    D)  15.4V

    Correct Answer: A

    Solution :

     \[{{\lambda }_{1}}=\frac{12375}{{{E}_{1}}(eV)}\overset{o}{\mathop{\text{A}}}\,=1000\overset{o}{\mathop{\text{A}}}\,\] \[\therefore \] \[{{E}_{1}}=12.375\,eV\]           ...(i) Similarly, \[{{E}_{2}}=\frac{12375}{{{\lambda }_{2}}(\overset{o}{\mathop{\text{A}}}\,)}\,eV\] \[=\frac{12375}{2000}\,=6.1875\,eV\] ?.(ii) Now,        \[{{E}_{1}}-{{W}_{0}}=e{{V}_{s}}\]         ...(iii) and       \[{{E}_{2}}-{{W}_{0}}=e{{V}_{s}}\]          ...(iv) Hence, \[12.375-{{W}_{0}}=7.7\,eV\]           ...(v) and        \[6.1875-{{W}_{0}}=e{{V}_{s}}\]           ...(vi) Solving, we get \[{{V}_{s}}=1.5\,V\]


You need to login to perform this action.
You will be redirected in 3 sec spinner