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JCECE Medical JCECE Medical Solved Paper-2008

  • question_answer
    Monochromatic    light    of   frequency \[\text{6}\text{.0}\,\text{ }\!\!\times\!\!\text{ }\,\,\text{1}{{\text{0}}^{\text{14}}}\text{ Hz}\]is produced by a laser. The power emitted is \[2\times {{10}^{-3}}W.\]The number of photons emitted, on the average, by the source per second is

    A) \[5\times {{10}^{15}}\]

    B)  \[5\times {{10}^{16}}\]

    C)  \[5\times {{10}^{17}}\]

    D)  \[5\times {{10}^{14}}\]

    Correct Answer: A

    Solution :

     Key Idea Photons are the packets of Power emitted, \[P=2\times {{10}^{-3}}W\] Energy of photon, \[E=hv=6.6\times {{10}^{-34}}\times 6\times {{10}^{14}}J\] where \[h\] being Planck's constant. Number of photons emitted per second \[n=\frac{P}{E}\] \[=\frac{2\times {{10}^{-3}}}{6.6\times {{10}^{-34}}\times 6\times {{10}^{14}}}=5\times {{10}^{15}}\]


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