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Compton effect

(Encyclopedia)Compton effect [for A. H. Compton], increase in the wavelengths of X rays and gamma rays when they collide with and are scattered from loosely bound electrons in matter. This effect provides strong ve...

stun gun

(Encyclopedia)stun gun, hand-held electronic device that produces a high-voltage pulse that can immobilize a person for several minutes with no permanent damage in most cases. It is powered by ordinary batteries, w...

Horkheimer, Max

(Encyclopedia)Horkheimer, Max hôrkˈhīˌmər, hôrˈkīˌ– [key], 1895–1973, German philosopher and sociologist. As director (1930–58) of the Institute for Social Research in Frankfurt, he played an importa...

occultation

(Encyclopedia)occultation ŏkˌəltāˈshən [key], in astronomy, eclipse of one celestial body by another, e.g., when the moon lies between a star and the earth. Occultations of stars by the moon are important in ...

Sailendra

(Encyclopedia)Sailendra sīlĕnˈdrä [key], name of a dynasty in Indonesia and SE Asia. The dynasty appeared in central Java in the 7th cent. and had consolidated its position by the mid-8th cent. The Sailendras, ...

spectrum

(Encyclopedia)CE5 Dispersion of white light by a triangular prism spectrum, arrangement or display of light or other form of radiation separated according to wavelength, frequency, energy, or some other propert...

loudspeaker

(Encyclopedia)CE5 Electrodynamic loudspeaker loudspeaker or speaker, device used to convert electrical energy into sound. It consists essentially of a thin flexible sheet called a diaphragm that is made to vibr...

Al-Battani

(Encyclopedia)Al-Battani ălˌbətēˈnēəs [key], b. before 858, d. 929, Arab astronomer and mathematician. He is best known in astronomy for his improvements and corrections of the Ptolemaic tradition. His Kitab...

Foch, Ferdinand

(Encyclopedia)Foch, Ferdinand fĕrdēnäNˈ fôsh [key], 1851–1929, marshal of France. A professor at the École de Guerre, he later served (1908–11) as director of that institute. In World War I, he was respon...

Keeler, James Edward

(Encyclopedia)Keeler, James Edward, 1857–1900, American astronomer, b. La Salle, Ill. At the age of 21 he went on the Naval Observatory expedition to Colorado to observe the solar eclipse of July, 1878. In 1886 h...