Problem 5.202

Find the free electron concentration in ionosphere if its refractive index is equal to $n=0.90$ for radiowaves of frequency $v=100 \mathrm{MHz}$

n_{0}=\left(4 \pi^{2} v^{2} m \varepsilon_{0} / e^{2}\right)\left(1-n^{2}\right)=2.4 \cdot 10^{7} \quad \mathrm{~cm}^{-3}

Dispersion and Absorption of Light