Radio is the wireless transmission of signals through free space by electromagnetic radiation of a frequency significantly below that of visible light, in the radio frequency range, from about 30 kHz to 300 GHz. These waves are called radio waves. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space.
Information, such as sound, is carried by systematically changing (modulating) some property of the radiated waves, such as their amplitude, frequency, phase, or pulse width. When radio waves strike an electrical conductor, the oscillating fields induce an alternating current in the conductor. The information in the waves can be extracted and transformed back into its original form.
Read more about Radio: Etymology, Processes, Communication Systems, Uses of Radio
Famous quotes containing the word radio:
“A bibulation of sports writers, a yammer of radio announcers, a guilt of umpires, an indigence of writers.”
—Walter Wellesley (Red)
“... the ... radio station played a Chopin polonaise. On all the following days news bulletins were prefaced by Chopin—preludes, etudes, waltzes, mazurkas. The war became for me a victory, known in advance, Chopin over Hitler.”
—Margaret Anderson (1886–1973)
“from above, thin squeaks of radio static,
The captured fume of space foams in our ears—”
—Hart Crane (1899–1932)