The maximum fequency for reflection of sky waves from a certain layer of the ionosphere is found to be `f_(max) =9(N_(max))^(1//2)`, Where N _max is the maximum electron density at that layer of the ionosphere.On a certain day it is observed that signals of frequencies higher than 5 MHz are not received by reflection from the `F_(1)` layer of the ionosphere while signals of frequencies higher than 8 MHz are not received by reflection from the `F_(2)` layer of the ionosphere. Estimate the maximum electron densities of the `F_(1)` and `F_(2)` layers on that day.

Answer

A, C

Explanation

From `f _(max) =9(N_(max))^(1/2`
`rArr N_(max)=(f_(max)^(2))/81`
`rArr N _(max)|_(F_1)=(5xx10^6)^2/81`
=` 0.3086xx 10^12 m^-13`
=`3.086 xx 10^11 m ^-3`
`and N_(max)|F_2=(8xx10^6)^2/81`
=`7.9 xx 10^11 m^-3`.