Optics Question 328
Question: For skywave propagation of a 10 MHz signal, what should be the minimum electron density in ionosphere
[AFMC 2005]
Options:
A) $ \tilde{\ }1.2\times 10^{12}{{m}^{-3}} $
B) $ \tilde{\ }10^{6}{{m}^{-3}} $
C) $ \tilde{\ }10^{14}{{m}^{-3}} $
D) $ \tilde{\ }10^{22}{{m}^{-3}} $
Show Answer
Answer:
Correct Answer: A
Solution:
If maximum electron density of the ionosphere is N max per m3 then the critical frequency fc is given by $ f _{c}=9{{({N _{\max }})}^{1/2}}. $
Therefore $ 1\times 10^{6}=9{{(N)}^{1/2}} $
Therefore N = 1.2 x 1012 m^-3
