JEE Main & Advanced Sample Paper JEE Main Sample Paper-5

  • question_answer
    Frequencies higher than 10 MHz were found not being reflected by the ionosphere on a particular day. The maximum electron density of the ionosphere on the day was near to

    A)  \[\tilde{\ }{{10}^{10}}/{{m}^{-3}}\]        

    B)  \[\tilde{\ }{{10}^{11}}{{m}^{-3}}\]

    C)  \[\tilde{\ }{{10}^{12}}{{m}^{-3}}\]           

    D)  \[\tilde{\ }{{10}^{13}}{{m}^{-3}}\]

    Correct Answer: C

    Solution :

     We know that \[fC=q\sqrt{{{N}_{\max }}}\] \[\Rightarrow \]\[{{N}_{\max }}=\frac{f{{C}^{2}}}{81}=\frac{{{(10\times {{10}^{6}})}^{2}}}{81}\] \[=\frac{{{10}^{14}}}{81}=1.24\times {{10}^{12}}/{{m}^{3}}\] \[={{10}^{12}}{{m}^{-3}}\]

You need to login to perform this action.
You will be redirected in 3 sec spinner