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arc, in electricity

(Encyclopedia)arc, in electricity, highly luminous and intensely hot discharge of electricity between two electrodes. The arc was discovered early in the 19th cent. by the English scientist Sir Humphry Davy, who so...

arc, in geometry

(Encyclopedia)arc, in geometry, a curved line or any part of it; in particular, a portion of the circumference of a circle. The length s of an arc of a circle of radius r and subtending a central angle of θ radian...

kite, in zoology

(Encyclopedia)kite, in zoology, common name for a bird of the family Accipitridae, which also includes the hawk. Kites are found near water and marshes in warm parts of the world. They prey chiefly on reptiles, fro...

labor, in economics

(Encyclopedia)labor, term used both for the effort of performing a task and for the workers engaged in the activity. In ancient times much of the work was done by slaves (see slavery). In the feudal period agricult...

Ariel, in astronomy

(Encyclopedia)Ariel ârˈēəl [key], in astronomy, one of the moons, or natural satellites, of Uranus. ...

lens, in optics

(Encyclopedia) CE5 Lenses lens, device for forming an image of an object by the refraction of light. In its simplest form it is a disk of transparent substance, commonly glass, with its two surfaces curved or wi...

Leo, in astronomy

(Encyclopedia)Leo [Lat.,=the lion], northern constellation lying S of Ursa Major and on the ecliptic (apparent path of the sun through the heavens) between Cancer and Virgo; it is one of the constellations of the z...

Larissa, in astronomy

(Encyclopedia)Larissa, in astronomy, one of the natural satellites, or moons, of Neptune. ...
 

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