JEE Main & Advanced Physics Communication System / संचार तंत्र Question Bank Self Evaluation Test - Communication System

  • question_answer
    In optical communication system operating at \[1200\text{ }nm,\] only \[2%\] of the source frequency is available for TV transmission having a bandwidth of \[5\text{ }MHz\]. What is the number of TV channels that can be transmitted?

    A) 1 million

    B) 50 million

    C) 1 thousand

    D) 50 thousand

    Correct Answer: A

    Solution :

    [a] Optical source frequency \[v=\frac{c}{\lambda }\] \[\Rightarrow \,\,\,\,\,\,\,\,v=\frac{3\times {{10}^{8}}m{{s}^{-1}}}{1200\times {{10}^{6}}m}=2.5\times {{10}^{14}}Hz\] Bandwidth of channel (\[2%\]of the source frequency) \[=5\times {{10}^{12}}Hz\] Number of channels \[=\frac{Total\text{ }bandwidth}{Bandwidth\text{ }needed\text{ }per\text{ }channel}\] \[=\frac{5\times {{10}^{12}}Hz}{5\times {{10}^{6}}Hz}={{10}^{6}}=1\] million.


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