NEET Sample Paper NEET Sample Test Paper-33

  • question_answer
    A light of wavelength \[5000\overset{\text{o}}{\mathop{\text{A}}}\,\] falls on a sensitive plate with photoelectric work function\[1.90eV\]. kinetic energy of the emitted photoelectrons is: (given,\[h=6.62\times {{10}^{-34}}J.S.\])

    A)  \[0.1\,eV\]             

    B)  \[2.5\,eV\]

    C)  \[0.58\,eV\]            

    D)  \[1.581\,eV\]

    Correct Answer: C

    Solution :

    From Einstein's photo electric equation \[{{E}_{K}}=E-W\] Where \[{{E}_{K}}\]is the kinetic energy of emitted photoelectrons, W the work function and the energy supplied. \[E=h\upsilon =\frac{hc}{\lambda }\] Where h is Planck's constant, c is the speed of light and \[\lambda \] the wavelength. \[\therefore \] \[E=\frac{6.6\times {{10}^{-34}}\times 3\times {{10}^{8}}}{5000\times {{10}^{-10}}}\] \[=3.96\times {{10}^{-19}}J\] Also,       \[1eV=1.6\times {{10}^{-19}}J\] So,           \[e=\frac{3.96\times {{10}^{-19}}}{1.6\times {{10}^{-19}}}=2.48eV\] Hence,  \[{{E}_{K}}=2.48-1.90=0.58eV.\]


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