Question

Which radiation is used for satellite communication?
A. Microwaves
B. X rays
C. Gamma rays
D. Infrared rays

Answer 1

Hint: You could think of the characteristics that would make a radiation ideal for satellite communication. Then, you could recall which among the given Electromagnetic waves has all these characteristics. Following these two steps, you will get the answer as well as justification for the same.

Complete answer:
In the question, we are asked to find which among the given electromagnetic waves is used for satellite communication.
It is the microwaves that are used for satellite communication. Now, if you wonder why microwave is preferred to other waves we could find out the characteristics of microwaves.
Microwaves are known to belong to the frequency range of 300MHz to 300GHz of the electromagnetic spectrum. One of their very special characteristics is the line of sight propagation. In line of sight propagation, the waves are known to travel in a direct path from the source to the receiver. In other words, we could say that no diffraction happens in the case of microwaves.
Another characteristic of microwaves is that their short wavelength aids the production of narrow beams of microwaves which further has an advantage of not interfering with nearby equipment using the same frequency and hence their frequency can be reused by nearby transmitters.
They also have high frequency that aids broad bandwidth and high data transmission rates and due to atmospheric ducting, they follow the curvature of the Earth and hence reach beyond the horizon.
These all characteristics make it ideal for being used in satellite communication.

Note:
We shouldn’t think that ‘Micro’ in microwaves means that its wavelength lies in the micrometer range. What actually says is that they are smaller than the radio waves in comparison. Point to point communication links, wireless networks, radar, medical diathermy, remote sensing, radio astronomy, spectroscopy, keyless entry systems, microwave radio relay networks and even in microwave ovens etc are some modern applications of microwaves.