JCECE Engineering JCECE Engineering Solved Paper-2007

  • question_answer
    For sky wave propagation of \[10\,\,MHz\] signal, what should be the minimum electron density in ionosphere?

    A)   \[\tilde{\ }1.2\times {{10}^{12}}{{m}^{-3}}\]

    B)  \[\tilde{\ }{{10}^{6}}{{m}^{-3}}\]

    C)  \[\tilde{\ }{{10}^{14}}{{m}^{-3}}\]

    D)   \[\tilde{\ }{{10}^{22}}{{m}^{-3}}\]

    Correct Answer: A

    Solution :

    The critical frequency of sky wave undergoing reflection from a layer of atmosphere is                 \[{{f}_{c}}=\sqrt[9]{{{N}_{\max }}}\] where \[N\] is electron density per\[{{m}^{3}}\]. \[\therefore \]  \[{{N}_{\max }}=\frac{{{f}_{c}}^{2}}{81}=\frac{{{(10\times {{10}^{6}})}^{2}}}{81}\]


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