Radio

Radio utilizes a small part of the electromagnetic spectrum, the set of related wave-based phenomena that includes radio along with infrared light, visible light, ultraviolet light, x rays, and gamma rays. Picture the electromagneticspectrum as a piano keyboard: radio will be located where the piano keys produce the low frequency musical notes. Radio waves have lengths from many miles down to a fraction of a foot.

Radio waves travel at the velocity of electromagnetic radiation. A radio signal moves fast enough to complete a trip around the earth in about 1/7 second.