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

  • question_answer
    The electron density of a layer of ionosphere at a height \[150\text{ }km\] from the earth's surface is \[9\times {{10}^{9}}\,per\,{{m}^{3}}.\]For the sky transmission from this layer up to a range of \[250\text{ }km,\]The critical frequency of the layer is

    A) \[2\,Hz\]

    B) \[2.7\,Hz\]

    C) \[2.78\,Hz\]

    D) \[2.7\,MHz\]

    Correct Answer: D

    Solution :

    [d] \[{{f}_{c}}=9\sqrt{{{N}_{m}}}=9\times \sqrt{9\times {{10}^{10}}}\] \[=2.7\times {{10}^{6}}Hz=2.7\,MHz\]


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