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:
“The radio ... goes on early in the morning and is listened to at all hours of the day, until nine, ten and often eleven o’clock in the evening. This is certainly a sign that the grown-ups have infinite patience, but it also means that the power of absorption of their brains is pretty limited, with exceptions, of course—I don’t want to hurt anyone’s feelings. One or two news bulletins would be ample per day! But the old geese, well—I’ve said my piece!”
—Anne Frank (1929–1945)
“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 o’clock arrived just once too often,”
—Kenneth Fearing (1902–1961)
“... 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)