Question

Assertion: - Microwave communication is preferred over optical communication.
Reason: - Microwaves provide a large number of channels and bandwidth compared to optical signals.
A. Both assertion and reason are true and the reason is the correct explanation of assertion.
B. Both assertion and reason are true and the reason is not the correct explanation of assertion.
C. Assertion is true but reason is false.
D. Both assertion and reason are false.

Answer 1

Hint: Microwave and visible light both fall in the category of electromagnetic waves and are a part of the electromagnetic spectrum. Communication by visible light is possible with the help of lasers and optical fibres.

Complete step-by-step answer:
Microwaves are invisible electromagnetic radiations that have wavelength in millimeter range. One of the major applications of microwaves is in communication. Convenient sized antennas can be directly appointed towards the receiver antenna and enable effective communication. They are majorly used in wireless communications. The range of microwave wavelength is from 0.1 mm to 1m. The range of visible light in terms of wavelength is about from 400 nm to 700 nm.
But these days Optical Fibre communication is preferred over other means of communications. Basically, a light for radiation emitted by a laser on one end can be transmitted to another end with the help of optical fibres using total internal reflection. The amount of information that can reach another end (with fibers) per unit time is far more compared to other means of communication. The signal undergoes less attenuation and is transmitted with considerably less interference (by noise signals). Besides, microwave communication is limited as it is a line of sight communication, no transmission can occur across obstacles like mountains, etc.
Therefore, the statement of assertion that microwave communication is preferred over optical communication is incorrect. So the reason obviously does not fit for the assertion.

Therefore, the correct answer is option (D).

Note: One can easily get confused here as the statement in the reason is a correct statement but it is not given in the option if the reason is correct. Besides as we already proved the assertion to be wrong the reason for it is going to be wrong. It is for the advances in Technologies in the field of optical communication that it is such a growing market these days.