What is the used of a frequency band?

A radio communications signal must occupy a range of frequencies carrying most of its energy, called its bandwidth. A frequency band may represent one communication channel or be subdivided into many . Allocation of radio frequency ranges to different uses is a major function of radio spectrum allocation.

Frequency describes the number of waves that pass a fixed place in a given amount of time . So if the time it takes for a wave to pass is is 1/2 second, the frequency is 2 per second. If it takes 1/100 of an hour, the frequency is 100 per hour.

In physics, the term frequency refers to the number of waves that pass a fixed point in unit time . It also describes the number of cycles or vibrations undergone during one unit of time by a body in periodic motion.

Communications. Radio frequencies are used in communication devices such as transmitters, receivers, computers, televisions, and mobile phones , to name a few. Radio frequencies are also applied in carrier current systems including telephony and control circuits.