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ampere
ampere , abbr. amp or A, basic unit of electric current. It is the fundamental electrical unit used with the mks system of units of the metric system . The ampere is officially defined as the current in a pair of equally long, parallel, straight wires 1 meter apart that produces a force of 0.0000...
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ohm
ohm ōm [for G. S. Ohm ], unit of electrical resistance , defined as the resistance in a circuit in which a potential difference of one volt creates a current of one ampere; hence, 1 ohm equals 1 volt/ampere. The megohm (1,000,000 ohms) and the milliohm (.001 ohm) are units derived from the ...
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ammeter
ammeter , instrument used to measure the magnitude of an electric current of several amperes or more. An ammeter is usually combined with a voltmeter and an ohmmeter in a multipurpose instrument. Most ammeters are based on the d'Arsonval galvanometer and are of the analog type, i.e., they give cur...
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Dachau
Dachau , city, Bavaria, S Germany, on the Amper River; chartered in 1391. It is a rail junction and its industries include the production of paper, cardboard, electrical equipment, and textiles. There is a 16th-century castle. Nearby was (1933-45) the first Nazi concentration camp , which today has...
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volt
volt [for Alessandro Volta ], abbr. V, unit of electric potential and electromotive force . It is defined as the difference of electric potential existing across the ends of a conductor carrying a constant current of 1 ampere when the power dissipated is 1 watt. The kilovolt (1,000 V), the mill...
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electric current
electric current Movement of electric charges, usually the flow of electrons along a conductor or the movement of ions through an electrolyte. This is caused by freely moving particles usually charged by a mains supply or battery. Current (symbol I) flows from a positive to a negative terminal, alt...
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André Marie Ampère
André Marie Ampère , 1775-1836, French physicist, mathematician, and natural philosopher. He was professor of mathematics at the École Polytechnique, Paris, and later at the Collège de France. Known for his contributions to electrodynamics, including the formulation of Am...
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International System of Units
International System of Units officially called the Système International d'Unités, or SI, system of units adopted by the 11th General Conference on Weights and Measures (1960). It is based on the metric system . The basic units of length, mass, and time are those of the mks system ...
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watt
watt [for James Watt ], abbr. W, unit of power, or work done per unit time, equal to 1 joule per second. It is used as a measure of electrical and mechanical power. One watt is the amount of power that is delivered to a component of an electric circuit when a current of 1 ampere flows through the ...
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transformer
transformer electrical device used to transfer an alternating current or voltage from one electric circuit to another by means of electromagnetic induction . The simplest type of transformer consists of two coils of wire, electrically insulated from one another and arranged so that a change in the...
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