NEET Sample Paper NEET Sample Test Paper-93

  • question_answer
    Light of wavelength \[200\overset{{}^\circ }{\mathop{A}}\,\] fall on aluminium surface. Work function of aluminium is 4.2 eV. What is the kinetic energy of the fastest emitted photoelectrons?

    A) 2 eV                 

    B)        1 eV

    C) 4 eV                 

    D)        0.2 eV

    Correct Answer: A

    Solution :

    [a] By Einstein's equation of photo-electric effect, the maximum kinetic energy of emitted photo-electrons is given by \[{{E}_{k}}=hv-W\]or \[{{E}_{k}}=\frac{hc}{\lambda }-W\] Where, h = Planck's constant v = frequency of incident light W= work function ofmetal \[\lambda \]= wavelength of incident light \[{{E}_{k}}=\frac{6.6\times {{10}^{-34}}\times 3\times {{10}^{8}}}{2000\times {{10}^{-10}}\times 1.6\times {{10}^{-19}}}eV-4.2eV\] So, \[{{E}_{k}}=2eV\]


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