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Classic radio receiver dial

Radio is the transmission of signals by modulation of [electromagnetic waves] with [frequencies] below those of [visible light] . Electromagnetic radiation [travels] by means of oscillating [electromagnetic field] s that pass through the air and the [vacuum] of space. Information is carried by systematically changing ( [modulating] ) some property of the radiated waves, such as [amplitude] , [frequency] , [phase] , or pulse width. When radio waves pass an electrical conductor, the oscillating fields induce an alternating current in the conductor. This can be [detected] and transformed into sound or other signals that carry information.

Originally, radio or radiotelegraphy was called " [wireless telegraphy] ", which was shortened to "wireless" by the British. The prefix radio- in the sense of wireless transmission, was first recorded in the word radioconductor , coined by the French physicist [Édouard Branly] in 1897 and based on the verb to radiate (in Latin "radius" means "spoke of a wheel, beam of light, ray"). "Radio" as a noun is said to have been coined by the advertising expert Waldo Warren (White 1944). This word also appears in a 1907 article by [Lee De Forest] , was adopted by the [United States Navy] in 1912 and became common by the time of the first commercial broadcasts in the United States in the 1920s. (The noun "broadcasting" itself came from an agricultural term, meaning "scattering seeds widely".) The term was then adopted by other languages in Europe and Asia. British Commonwealth countries continued to mainly use the term "wireless" until the mid 20th century, though the magazine of the [BBC] in the UK has been called [Radio Times] ever since it was first published in the early 1920s.

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