Question

In short wave communication waves of which of the following frequencies will be reflected back by the ionospheric layer, having electron density ${10}^{11}$ per $m^3$

• A. 2 MHz
• B. 10 MHz
• C. 12 MHz
• D. 18 MHz

Answer 1

The correct option is A 2 MHz

By using $f_c\approx 9{\left(N_{max}\right)}^{\frac{1}{2}}\Rightarrow f_c\approx 2MHz$