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

Options

A. `~ 1.2 xx 10^(12) m^(-3)`
B. `~10^(6) m^(-3)`
C. `~2.3 xx 10^(-4) m^(-3)`
D. `~ 10^(22) m^(-3)`

Answer

A

Explanation

We know that `, f_(c)=9(N_("max"))^(1//2)`
` or 10 xx 10^(6)=9(N_("max"))^(1//2)`
`implies (10^(7))/(9)=(N_("max"))^(1//2)`
`or (10^(14))/(81)=N_("max")implies (100)/(81) xx 10^(12)=N_("max")`
`N_("max")~~1.2 xx 10^(12) m^(-3)`