electric current

electric current
the time rate of flow of electric charge, in the direction that a positive moving charge would take and having magnitude equal to the quantity of charge per unit time: measured in amperes. Also called current, electricity.
[1830-40]

* * *

Movement of electric charge carriers.

In a wire, electric current is a flow of electrons that have been dislodged from atoms and is a measure of the quantity of electrical charge passing any point of the wire per unit time. Current in gases and liquids generally consists of a flow of positive ions in one direction together with a flow of negative ions in the opposite direction. Conventionally, the direction of electric current is that of the flow of the positive ions. In alternating current (AC) the motion of the charges is periodically reversed; in direct current (DC) it is not. A common unit of current is the ampere, a flow of one coulomb of charge per second, or 6.24 × 1018 electrons per second.

* * *

      any movement of electric charge carriers, such as subatomic charged particles (e.g., electrons having negative charge, protons having positive charge), ions (atoms that have lost or gained one or more electrons), or holes (electron deficiencies that may be thought of as positive particles).

      Electric current in a wire, where the charge carriers are electrons, is a measure of the quantity of charge passing any point of the wire per unit of time. In alternating current (q.v.) the motion of the electric charges is periodically reversed; in direct current (q.v.) it is not. In many contexts the direction of the current in electric circuits is taken as the direction of positive charge flow, the direction opposite to the actual electron drift. When so defined the current is called conventional current.

      Current in gases and liquids generally consists of a flow of positive ions in one direction together with a flow of negative ions in the opposite direction. To treat the overall effect of the current, its direction is usually taken to be that of the positive charge carrier. A current of negative charge moving in the opposite direction is equivalent to a positive charge of the same magnitude moving in the conventional direction and must be included as a contribution to the total current. Current in semiconductors consists of the motion of holes in the conventional direction and electrons in the opposite direction.

      Currents of many other kinds exist, such as beams of protons, positrons, or charged pions and muons in particle accelerators.

      Electric current generates an accompanying magnetic field, as in electromagnets. When an electric current flows in an external magnetic field, it experiences a magnetic force, as in electric motors. The heat loss, or energy dissipated, by electric current in a conductor is proportional to the square of the current.

      A common unit of electric current is the ampere, a flow of one coulomb of charge per second, or 6.2 × 1018 electrons per second. The centimetre–gram–second units of current are either the electrostatic unit of charge (esu) per second or the absolute electromagnetic unit (abamp). One abamp equals 10 amps; 1 amp equals 3 × 109 esu per second.

      Commercial power lines make available about 100 amps to a typical home; a lightbulb pulls about 1 amp of current and a one-room air conditioner about 15 amps.

* * *


Universalium. 2010.

Игры ⚽ Нужно сделать НИР?

Look at other dictionaries:

  • Electric current — Electric E*lec tric ([ e]*l[e^]k tr[i^]k), Electrical E*lec tric*al ([ e]*l[e^]k tr[i^]*kal), a. [L. electrum amber, a mixed metal, Gr. h lektron; akin to hle ktwr the beaming sun, cf. Skr. arc to beam, shine: cf. F. [ e]lectrique. The name came… …   The Collaborative International Dictionary of English

  • electric current — electric current, electrical current electrical current, the movement of electrically charged particles, atoms, or ions, through solids, liquids, gases, or free space; the term is usually used of relatively smooth movements of electric charge… …   The Collaborative International Dictionary of English

  • Electric current — Electromagnetism …   Wikipedia

  • electric current — Electricity E lec*tric i*ty ([=e] l[e^]k*tr[i^]s [i^]*t[y^]), n.; pl. {Electricities} ([=e] l[e^]k*tr[i^]s [i^]*t[i^]z). [Cf. F. [ e]lectricit[ e]. See {Electric}.] 1. (Physics) a property of certain of the fundamental particles of which matter… …   The Collaborative International Dictionary of English

  • electric current — noun a flow of electricity through a conductor (Freq. 4) the current was measured in amperes • Syn: ↑current • Hypernyms: ↑electrical phenomenon • Hyponyms: ↑juice, ↑ …   Useful english dictionary

  • electric current — the stream of electricity that moves along a conductor. Symbol I. An electric current is due to a difference of potential between two points, this difference being measured in volts. The volume of flow depends on the difference of potential and… …   Medical dictionary

  • electric current — elektros srovės stipris statusas T sritis Standartizacija ir metrologija apibrėžtis Elektros kiekis, per vienetinį laiko tarpą pratekantis per laidininko skerspjūvį. Elektros srovės stipris yra vienas iš pagrindinių SI dydžių. atitikmenys: angl.… …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

  • electric current — elektros srovė statusas T sritis automatika atitikmenys: angl. electric current vok. elektrischer Strom, m rus. электрический ток, m pranc. courant électrique, m …   Automatikos terminų žodynas

  • electric current — elektros srovė statusas T sritis Standartizacija ir metrologija apibrėžtis Kryptingas krūvininkų judėjimas. atitikmenys: angl. electric current vok. elektrischer Strom, m rus. электрический ток, m pranc. courant électrique, m …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

  • electric current — elektros srovė statusas T sritis chemija apibrėžtis Kryptingas krūvininkų judėjimas. atitikmenys: angl. electric current rus. электрический ток …   Chemijos terminų aiškinamasis žodynas

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”