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.
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)
“A liberal is a socialist with a wife and two children.”
—Anonymous. BBC Radio 4 (April 8, 1990)
“Local television shows do not, in general, supply make-up artists. The exception to this is Los Angeles, an unusually generous city in this regard, since they also provide this service for radio appearances.”
—Fran Lebowitz (b. 1950)