Q. The relation between the maximum electron density $N_{\max}$ and the critical frequency $f_{c}$ for the ionosphere can be given as
A) $f_{c} = \sqrt{9\ N_{\max}}$
B) $f_{c} = \sqrt{9\ }N_{\max}$
C) $f_{c} = 9\sqrt{\ N_{\max}}$
D) None of these
Explanation
(c) If maximum electron density of the ionosphere in $N_{\max}$ per $m^{3},$ then $f_{c} = 9\left( N_{\max} \right)^{1/2}.$ Above $f_{c},$ a wave will penetrate the ionosphere and is not reflected by it.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.