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:
“Having a thirteen-year-old in the family is like having a general-admission ticket to the movies, radio and TV. You get to understand that the glittering new arts of our civilization are directed to the teen-agers, and by their suffrage they stand or fall.”
—Max Lerner (b. 1902)
“Denouement to denouement, he took a personal pride in the
certain, certain way he lived his own, private life,
but nevertheless, they shut off his gas; nevertheless,
the bank foreclosed; nevertheless, the landlord called;
nevertheless, the radio broke,
And twelve oclock arrived just once too often,”
—Kenneth Fearing (19021961)
“... 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)