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:
“All radio is dead. Which means that these tape recordings Im making are for the sake of future history. If any.”
—Barré Lyndon (18961972)
“... the ... radio station played a Chopin polonaise. On all the following days news bulletins were prefaced by Chopinpreludes, etudes, waltzes, mazurkas. The war became for me a victory, known in advance, Chopin over Hitler.”
—Margaret Anderson (18861973)
“We spend all day broadcasting on the radio and TV telling people back home whats happening here. And we learn whats happening here by spending all day monitoring the radio and TV broadcasts from back home.”
—P.J. (Patrick Jake)