Question

If the critical frequency for sky wave propagation is 12 MHz, then the maximum electron density in the ionosphere is

• A. $1.78 \times 10^{12}\, m^{-3}$
• B. $0.178 \times 10^{10}\, m^{-3}$
• C. $1.12 \times 10^{12}\, m^{-3}$
• D. $0.56 \times 10^{12}\, m^{-3}$

Answer 1

Answer: (A)

$1.78 \times 10^{12}\, m^{-3}$

Answer 2

Critical frequency for sky wave propagation
\hspace30mm f_c = 9\, (N_{max})^{1/2}
or \hspace20mm N_{max}= \frac{f_c^2}{81} = \frac{(12 \times 10^6)^2}{81} =1.78 \times 10^{12}\, m^{-3}