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volt[for Alessandro VoltaVolta, Alessandro, Conte
, 1745–1827, Italian physicist. He was professor of physics at the Univ. of Pavia from 1779 and became famous for his work in electricity. Napoleon I made him a count and a senator of the kingdom of Lombardy.
..... Click the link for more information. ], abbr. V, unit of electric potentialpotential, electric,
work per unit of electric charge expended in moving a charged body from a reference point to any given point in an electric field (see electrostatics).
..... Click the link for more information. and electromotive forceelectromotive force,
abbr. emf, difference in electric potential, or voltage, between the terminals of a source of electricity, e.g., a battery from which no current is being drawn. When current is drawn, the potential difference drops below the emf value.
..... Click the link for more information. . 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 millivolt (0.001 V), and the microvolt (0.000001 V) are units derived from the volt. See voltmetervoltmeter,
instrument used to measure differences of electric potential, commonly called voltage, in volts or units that are multiples or fractions of volts. A voltmeter is usually combined with an ammeter and an ohmmeter in a multipurpose instrument.
..... Click the link for more information. .
a unit of electrical voltage, electrical potential difference, and electromotive force (emf), which is included in the International System of Units. It is named after the Italian scientist A. Volta and is designated by the letter V. It was adopted at the First International Congress of Electricians in 1881 as a practical unit of emf equal to 108 units in the cgs system of units. From 1893 to 1948 the international volt (Vint) was used. It was equal to the voltage or emf which in a conductor having a resistance of 1 Oint produced a current of 1 Aint. An accurate value was established for the international volt by a standard consisting of a group of normal Weston cells. With the change in 1948 to the system of absolute practical electrical units, the volt (Vabs) became a derived unit which is used in the International System of Units: 1 V is the electrical voltage that in an electrical circuit produces a direct current of 1 ampere when dissipating a power of 1 watt.
The unit for potential difference in the cgs electrostatic system and the cgs system is equal to 300 Vabs (more accurately 10-8·c V, where c is the numerical value of the velocity of light in a vacuum expressed in cm/sec). 1 Vint = 1.00035 Vabs.