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^(-1)`
C. `~10^(14)m^(-3)`
D. `~10^(22) m^(-3)`

Answer

A

Explanation

The critical frequency of a sky wave for reflection from a layer of atmosphere is given by `f_(c)=9(N_("max"))^(1//2)`
where N is the density of electron `"/"M^(3)`.
`10xx10^(6)=9(N_("max"))^(1//2)`
`N_("max")=((10xx10^(6))/(9))^(2)cong 1.2xx10^(12) m^(-3)`.