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British thermal unit
(Encyclopedia)British thermal unit, abbr. Btu, unit for measuring heat quantity in the customary system of English units of measurement, equal to the amount of heat required to raise the temperature of one pound of...blackbody
(Encyclopedia)blackbody, in physics, an ideal black substance that absorbs all and reflects none of the radiant energy falling on it. Lampblack, or powdered carbon, which reflects less than 2% of the radiation fall...kelvin
(Encyclopedia)kelvin, abbr. K, official name in the International System of Units (SI) for the degree of temperature as measured on the Kelvin temperature scale. ...Le Châtelier's principle
(Encyclopedia)Le Châtelier's principle, chemical principle that states that if a system in equilibrium is disturbed by changes in determining factors, such as temperature, pressure, and concentration of components...hardening
(Encyclopedia)hardening, in metallurgy, treatment of metals to increase their resistance to penetration. A metal is harder when it has small grains, which result when the metal is cooled rapidly. Sometimes small ar...vapor pressure
(Encyclopedia)vapor pressure, pressure exerted by a vapor that is in equilibrium with its liquid. A liquid standing in a sealed beaker is actually a dynamic system: some molecules of the liquid are evaporating to f...superconductivity
(Encyclopedia)superconductivity, abnormally high electrical conductivity of certain substances. The phenomenon was discovered in 1911 by Heike Kamerlingh Onnes, who found that the resistance of mercury dropped sudd...Saha, Meghnad
(Encyclopedia)Saha, Meghnad māgnädˈ säˈhä [key], 1893–1956, Indian physicist. He was a professor at Allahabad Univ. from 1923 to 1938 and a professor and physics department head at Calcutta Univ. from 1938....liquid crystal
(Encyclopedia)liquid crystal, liquid whose component particles, atoms or molecules, tend to arrange themselves with a degree of order far exceeding that found in ordinary liquids and approaching that of solid cryst...phase diagram
(Encyclopedia) CE5 Phase diagram for a substance, like water, which expands on freezing phase diagram, graph that shows the relation between the solid, liquid, and gaseous states of a substance (see states of ma...Browse by Subject
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