Assertion: Television signals are received through sky-wave propagation.
Reason: The ionosphere reflects electromagnetic waves of frequencies greater than a certain critical frequency
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false
D.
If both assertion and reason are false
In skywave 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 penetrates the ionosphere and is not reflected back by the ionosphere. The TV signal having frequency greater than 30 MHz therefore cannot be propagated through sky wave propagation.
In case of skywave propagation, critical frequency is defined as the highest frequency that is returned to the earth by the considered layer of the ionosphere after having sent straight to it. Above this frequency, a wave will penetrate the ionosphere and is not reflected by it.
Assertion: Microwave communication is peferred over optical communication.
Reason: Microwaves provide large number of channels and bandwidth compared to optical signals.
if both assertion and reason are true but reason is the correct explanation of assertion
if both assertion and reason are true and the reason is not the correct explanation of assertion
if assertion is true and reason is false
if both assertion and reason are false statements
Assertion: In high latitudes one sees colourful curtains of light hanging down from high altitudes.
Reason: The high energy charged particles from the are deflected to polar regions by the magnetic field of the earth.
if both assertion and reason are true and the reason is the correct explanation of the assertion
if both assertion and reason are true and the reason is not the correct explanation of the assertion
if assertion is true but reason is false
if both assertion and reason are false statements
High-frequency waves are
affected by the solar cycle
reflected by layer
absorbed by the
capable of use for long-distance communication on the moon
The principle of LASER action involves
amplification of particular frequency emitted by the system
population inversion
stimulated emission
All of the above
Through which mode of propagation, the radio waves can be sent from one place to another?
Ground wave propagation
Sky wave propagation
Space wave propagation
All of the above