CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2009

  • question_answer
    In optical communication system operating at 1200 nm, only 2% of the source frequency is available for TV transmission having a bandwidth of 5 MHz. The number of TV channels that can be transmitted is

    A)  2 million         

    B)         10 million           

    C)         0.1 million       

    D)         1 million

    E)  0.5 million

    Correct Answer: D

    Solution :

    The frequency for optical communication \[v=\frac{c}{\lambda }\] or        \[v=\frac{3\times {{10}^{8}}}{1200\times {{10}^{-9}}}\] \[v=25\times {{10}^{13}}Hz\] But only 2% of the source frequency is available for TV transmission. \[\therefore \] \[v=2.5\times {{10}^{14}}\times 2%\] or            \[v=2.5\times {{10}^{14}}\times \frac{2}{100}\] or            \[v=5\times {{10}^{12}}Hz\] \[\therefore \]Number of channels\[=\frac{v}{bandwidth}\] or number of channels\[=\frac{5\times {{10}^{12}}}{5\,MHz}\] or number of channels\[=\frac{5\times {{10}^{12}}}{5\times {{10}^{6}}}\] \[={{10}^{6}}\] = 1 million


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