direct current, abbr. DC, a movement of electric charge across an arbitrarily defined surface in one direction only. See electricity; generator.

direct action, theory and methods used by certain labor groups to fight employers, capitalist institutions, and the state by direct economic action, without using intermediate organizations. Political measures, such as arbitration, collective bargaining, and trade agreements, are rejected as ineffective. According to the theory, workers, acting as a class, are in a position to exert pressure on capitalist institutions to secure rights. Such measures as the strike, the general strike, the boycott, and sabotage—frequently accompanied by physical violence—are the preferred methods for labor disputes; propaganda and agitation are employed against the government. The specific reforms gained are seen as steps toward the ultimate revolution and toward abolition of capitalism. The theory was developed with the rise of the labor movement in the 19th cent. and was formulated as a definite policy in the early 20th cent. by anti-Marxist radical groups, notably proponents of syndicalism. The method was used in France and spread to other European countries. In the United States the Industrial Workers of the World advocated it.

Flow of electric charge that does not change direction. Direct current is produced by batteries, fuel cells, rectifiers, and generators with commutators. Direct current was supplanted by alternating current (AC) for common commercial power in the late 1880s because it was then uneconomical to transform it to the high voltages needed for long-distance transmission. Techniques developed in the 1960s overcame this obstacle, and direct current is now transmitted over very long distances, though it must ordinarily be converted to alternating current for final distribution. For some uses, such as electroplating, direct current is essential.

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