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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 fields 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, or phase. 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. The meaning and usage of the word "radio" has developed in parallel with developments within the field and can be seen to have three distinct phases electromagnetic waves and experimentation; wireless communication and technical development; and radio broadcasting and commercialization. Many, many individuals -- inventors, engineers, developers, businessmen -- contributed to produce the modern idea of radio and thus the origins and 'invention' are multiple and controversial. In 1893, Nikola Tesla, in America, first demonstrated the principles of wireless communications.[1][2] Tesla would later ultimately hold the patent rights in the United States. [3] Physicists and inventors such as John Stone Stone and Alexander Stepanovich Popov have cited Tesla as the originator of wireless communications.[4] In August 1894, Oliver Lodge, an English physicist and writer, transmitted radio signals at a meeting of the British Association for the Advancement of Science at the University of Oxford.[5] In 1895, Guglielmo Marconi, an Italian inventor, began experimenting with wireless and went on to develop the world's first commercial system of radio communication. In 1896, Marconi was granted the world's first wireless telegraphy patent by the British Patent Office. Marconi has been generally credited with the development of radio by most scholars and historians.[6] [7] [8] [9] [10] In 1909, Marconi was jointly awarded the Nobel Prize for Physics with Karl Ferdinand Braun "in recognition of their contributions to the development of wireless telegraphy."[11] Originally, radio or radiotelegraphy was called "wireless telegraphy", which was shortened to "wireless". The prefix radio- in the sense of wireless transmission, was first recorded in the word radioconductor, coined by the French physicist Edouard 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 advertising expert Waldo Warren (White 1944). The word 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".) The term was then adopted by other languages in Europe and Asia, although British Commonwealth countries continued to use the term "wireless" until the mid-20th century.
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