Question

Frequencies higher than $10MHz$ are found not to be reflected by the particles present in the ionosphere then what is the maximum electron density of the ionosphere?

• A. $\frac{{10}^{14}}{81}e{m}^{-3}$
• B. ${10}^{14}e{m}^{-3}$
• C. ${10}^{4}e{m}^{-3}$
• D. $\frac{{10}^{14}}{7}e{m}^{-3}$

Answer 1

Answer: (A)

$\frac{{10}^{14}}{81}e{m}^{-3}$

Given,

Critical frequency $\left(f_c\right)=10MHz={10}^{7}Hz$

Let maximum electrons density in the ionosphere be $N_{max}$

The relation between the critical frequency and the maximum electron density of the ionosphere is given by the expression:

$f_c=9\times (N_{max}{)}^{1/2}$

$N_{max}=\frac{f_c^2}{81}$

$N_{max}=\frac{{10}^{14}}{81}$

So, the answer will be option$\left(A\right)$