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angstrom

(Encyclopedia)angstrom ăngˈstrəm [key], abbr. Å, unit of length equal to 10−10 meter (0.0000000001 meter); it is used to measure the wavelengths of visible light and of other forms of electromagnetic radiatio...

mole, in chemistry

(Encyclopedia)mole, in chemistry, a quantity of particles of any type equal to Avogadro's number, or 6.02×1023 particles. One gram-molecular weight of any molecular substance contains exactly one mole of molecules...

Ohm, Georg Simon

(Encyclopedia)Ohm, Georg Simon gāˈôrkh zēˈmôn ōm [key], 1787–1854, German physicist. He was professor at Munich from 1852. His study of electric current led to his formulation of the law now known as Ohm's...

light-year

(Encyclopedia)light-year, in astronomy, unit of length equal to the distance light travels in one sidereal year. It is 9.461 × 1012 km (about 6 million million mi). Alpha Centauri and Proxima Centauri, the stars n...

Maillart, Robert

(Encyclopedia)Maillart, Robert mīyärˈ [key], 1872–1940, Swiss engineer, renowned for his inventive and beautiful reinforced-concrete bridges. Maillart's basic structural principles—integration of the support...

Kennewick

(Encyclopedia)Kennewick kĕnˈəwĭk [key], city (1990 pop. 42,155), Benton co., SE Wash., on the Columbia River near the influx of the Snake River, in an irrigated farm and vineyard region; inc. 1904. With Richlan...

barn

(Encyclopedia)barn, abbr. b, in physics, unit of nuclear cross section, i.e., the effective target presented by a nucleus for collisions leading to nuclear reactions; it is equal to 10−24 square centimeters. The ...

South Pass

(Encyclopedia)South Pass, broad, level valley (alt. c.7,550 ft/2,301 m), SW Wyo., cutting across the Rocky Mts. It was used by trappers and explorers before Jedediah Smith inaugurated its use as a route for settler...

equivalent weight

(Encyclopedia)equivalent weight. The equivalent weight of an element or radical is equal to its atomic weight or formula weight divided by the valence it assumes in compounds. The unit of equivalent weight is the a...

syndicalism

(Encyclopedia)syndicalism sĭnˈdĭkəlĭzəm [key], political and economic doctrine that advocates control of the means and processes of production by organized bodies of workers. Like anarchists, syndicalists bel...