Monday, November 24, 2008

Electric Arc: Voltaic Arc

An electric arc is a continuous electric discharge of high current between two carbon points as electrodes, forming a luminous arc of intense brilliancy and heat by the passage of a powerful voltaic current. The phenomenon is exploited in the carbon-arc lamp, once widely used in film projectors. In the electric-arc furnace an arc struck between very large carbon electrodes and the metal charge provides the heating. In arc welding an electric arc provides the heat to fuse the metal. The discharges in low-pressure gases, as in neon and sodium lights, can also be broadly considered as electric arcs.

Also known as voltaic arc, the various shapes of electric arc are emergent properties of nonlinear patterns of current and electric field and it results in a very high temperature, capable of melting or vaporizing most materials. Industrially, electric arcs are used for welding, plasma cutting, for electrical discharge machining, as an arc lamp in movie theater projectors, and followspots in stage lighting.