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lanthanide series

(Encyclopedia)lanthanide series, a series of metallic elements, included in the rare-earth metals, in Group 3 of the periodic table. Members of the series are often called lanthanides, although lanthanum (atomic nu...

administrative law

(Encyclopedia)administrative law, law governing the powers and processes of administrative agencies. The term is sometimes used also of law (i.e., rules, regulations) developed by agencies in the course of their op...

solar constant

(Encyclopedia)solar constant, the average amount of radiant energy received by the earth's atmosphere from the sun; its value is about 2 calories per min incident on each square centimeter of the upper atmosphere. ...

exclusion principle

(Encyclopedia)exclusion principle, physical principle enunciated by Wolfgang Pauli in 1925 stating that no two electrons in an atom can occupy the same energy state simultaneously. The energy states, or levels, in ...

laser

(Encyclopedia)CE5 Ordinary light sources produce incoherent light, while a laser produces a beam of coherent light. laser [acronym for light amplification by stimulated emission of radiation], device for the cr...

ecology

(Encyclopedia)ecology, study of the relationships of organisms to their physical environment and to one another. The study of an individual organism or a single species is termed autecology; the study of groups of ...

civil time

(Encyclopedia)civil time, local time based on universal time. Civil time may be formally defined as mean solar time plus 12 hr; the civil day begins at midnight, while the mean solar day begins at noon. Civil time ...

Fuchs, Klaus Emil

(Encyclopedia)Fuchs, Klaus Emil fo͝oks, fo͞oks [key], 1912–88, British physicist and Communist spy, b. Germany. In 1933 he fled Germany for England, where he completed his education. Interned (1940–41) in Can...

mass, in physics

(Encyclopedia)mass, in physics, the quantity of matter in a body regardless of its volume or of any forces acting on it. The term should not be confused with weight, which is the measure of the force of gravity (se...

sonar

(Encyclopedia)sonar sōˈnär [key], device used underwater for locating submerged objects and for submarine communication by means of sound waves. The term sonar is an acronym for sound navigation ranging. The mai...