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

Options

A. `1-2xx10^(8)m^(-3)`
B. `1-2xx10^(12)m^(-3)`
C. `1-2xx10^(14)m^(-3)`
D. `1-2xx10^(16)m^(-3)`

Explanation

As, `v_(c)=9(N_("max"))^(1//2)`
or `N_("max")=((v_(c))/(9))^(2)=(v_(c)^(2))/(81) =((10xx10^(6))^(2))/(81)`
`=1.2xx10^(12)m^(-3)`