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The Luminous Arc

المؤلف:  GEORGE A. HOADLEY

المصدر:  ESSENTIALS OF PHYSICS

الجزء والصفحة:  p-422

2025-12-24

645

The ordinary carbon arc itself is not luminous, the light coming from the hot crater of the positive carbon. If, however, carbons are used which have a core made of a mixture of carbon and some metallic salts, the hot vapors given off by these salts become luminous when heated by the current. If calcium salts are used, the color is a golden yellow, and this arc is sometimes called the flaming arc, from its resemblance to a flame. The arc formed is much longer than the ordinary carbon arc and the light is exceedingly brilliant.

Another exceedingly brilliant source of light is the magnetite arc. This has a heavy copper rod for the positive upper terminal and a tube of sheet iron, packed with the mineral magnetite for the lower. The terminals wear away very slowly and the lamp is of high efficiency.