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Sarnoff, David

(Encyclopedia)Sarnoff, David, 1891–1971, American pioneer in radio and television, b. Russia. Emigrating to the United States in 1900, he worked for the Marconi Wireless Company, winning recognition as the narrat...

Paley Center for Media

(Encyclopedia)Paley Center for Media, American archive of radio and television programs, and forum for the discussion of the role and evolution of electronic media as well as the intersections of media and society;...

Saca González, Elías Antonio

(Encyclopedia)Saca González, Elías Antonio ālēˈäs äntōˈnēō säˈkä gōnsälˈās [key], 1965–, Salvadoran political leader, president of El Salvador (2004–9), b. Usulután. “Tony” Saca worked as...

black hole

(Encyclopedia)black hole, in astronomy, celestial object of such extremely intense gravity that it attracts everything near it and in some instances prevents everything, including light, from escaping. The term was...

altimeter

(Encyclopedia)altimeter ăltĭmˈĭtər, ălˈtĭmēˌtər [key], device for measuring altitude. The most common type is an aneroid barometer calibrated to show the drop in atmospheric pressure in terms of linear e...

ionosphere

(Encyclopedia)ionosphere īŏnˈəsfēr [key], series of concentric ionized layers forming part of the upper atmosphere of the earth from around 30 to 50 mi (50 to 80 km) to 250 to 370 mi (400 to 600 km) where it m...

microphone

(Encyclopedia)microphone, device for converting sound into electrical energy, used in radio broadcasting, recording, and sound amplifying systems. Its basic component is a diaphragm that responds to the pressure or...

Armstrong, Edwin Howard

(Encyclopedia)Armstrong, Edwin Howard, 1890–1954, American engineer and radio inventor, b. New York City, grad. Columbia (E.E. 1913). He was associated in research with Michael I. Pupin at Columbia and became pro...

AM, abbreviation for amplitude modulation

(Encyclopedia)AM: see modulation; radio. ...