Answer to Question #122676 in Physics for kashaf

Question

The plasma density in the lower ionosphere has been measured during satellite re-entry to be about 10^18 m^-3 at 50km altitude,10^17at 70 km,and 10^14 at 8 km.what are the plasma frequencies there?...... please solve it completely

Answer 1

The plasma frequency, depending on the number density n, charge of electron e, and mass m is

$$f=\frac{1}{2\pi}\sqrt{\frac{ne^2}{m\epsilon_0}}.$$

At 8 km:

$$f=224\cdot10^{15}\text{ Hz},$$

at 50 km:

$$f=22.4\cdot10^{18}\text{ Hz},$$

at 70 km:

$$f=7.09\cdot10^{15}\text{ Hz}.$$