Statement-I : Television signals are received through sky-wave propagation
Statement-II : The ionosphere reflects electromagnetic waves of frequencies greater than a certain critical frequency.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion
B. If both assertion and reason are true but reason is not the correct explanation of assertion
C. If assertion is true but reason is false
D. If both assertion and reason are false

Answer

D

Explanation

In sky wave propagation, the radio waves having frequency range 2 MHz to 30 MHz are reflected back by the ionosphere. Radio waves having frequency nearly greater than 30 MHz therefore cannot be propagated through sky wave propagation. In case of sky wave propagation, critical frequency is defined as the highest frequency that is returned to the earth by the considered layer of the ionosphere after having straight to it. Above this frequency, a wave. will penetrale the ionosphere and is not reflected by it.