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:
“England has the most sordid literary scene I’ve ever seen. They all meet in the same pub. This guy’s writing a foreword for this person. They all have to give radio programs, they have to do all this just in order to scrape by. They’re all scratching each other’s backs.”
—William Burroughs (b. 1914)
“Now they can do the radio in so many languages that nobody any longer dreams of a single language, and there should not any longer be dreams of conquest because the globe is all one, anybody can hear everything and everybody can hear the same thing, so what is the use of conquering.”
—Gertrude Stein (1874–1946)
“A liberal is a socialist with a wife and two children.”
—Anonymous. BBC Radio 4 (April 8, 1990)