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Tennessee Valley Authority

(Encyclopedia)Tennessee Valley Authority (TVA), independent U.S. government corporate agency, created in 1933 by act of Congress; it is responsible for the integrated development of the Tennessee River basin. The h...

Castro, Fidel

(Encyclopedia)Castro, Fidel (Fidel Alejandro Castro Ruz) käsˈtrō [key], 1926–2016, Cuban revolutionary, premier of Cuba (1959–76), president of the Council of State and of the Council of Ministers (1976–2...

photoelectric effect

(Encyclopedia)photoelectric effect, emission of electrons by substances, especially metals, when light falls on their surfaces. The effect was discovered by H. R. Hertz in 1887. The failure of the classical theory ...

phosphorylation

(Encyclopedia)phosphorylation, chemical process in which a phosphate group is added to an organic molecule. In living cells phosphorylation is associated with respiration, which takes place in the cell's mitochondr...

hydrophone

(Encyclopedia)hydrophone hīˈdrəfōnˌ [key], device that receives underwater sound waves and converts them to electrical energy; the voltage generated can then be read on a meter or played through a loudspeaker....

erg

(Encyclopedia)erg ûrg [key], unit of work or energy in the cgs system of units, which is based on the metric system; it is the work done or energy expended by a force of 1 dyne acting through a distance of 1 centi...

foot-pound

(Encyclopedia)foot-pound, abbr. ft-lb, unit of work or energy in the customary English gravitational system; it is the work done or energy expended by a force of 1 pound acting through a distance of 1 foot. It is e...

phonon

(Encyclopedia)phonon fōˈnŏn [key], quantum of vibrational energy. The atoms of any crystal are in a state of vibration, their average kinetic energy being measured by the absolute temperature of the crystal. In ...

Kazakhstan

(Encyclopedia)CE5 Kazakhstan or Kazakstan käˌzäkstänˈ [key], officially Republic of Kazakhstan, republic (2015 est. pop. 17,750,000), c.1,050,000 sq mi (2,719,500 sq km), central Asia. It borders on Siberia...

photosynthesis

(Encyclopedia)photosynthesis fōˌtōsĭnˈthəsĭs [key], process in which green plants, algae, and cyanobacteria utilize the energy of sunlight to manufacture carbohydrates from carbon dioxide and water in the pr...