For sky wave propagation of a `10 MHz` signal, what should be the minimum electron density in ionosphere?

Options

A. `~1.2xx10^(12) m^(-3)`
B. `~10^(6) m^(-3)`
C. `~10^(14) m^(-3)`
D. `~10^(22) m^(-3)`

Answer

a

Explanation

If maximum electron density of the ionosphere is `N_(max) "per "m^(3)` then the critical frequency `f_(c)` is given by `f_(c)=9(N_(max))^(1//2)`
`implies1xx10^(6)=9(N)^(1//2) implies N=1.2xx10^(12) m^(-3)`