Primary
Current (I) ○◂｜Definition｜1st｜20251119205401-00-⌔
Electric current
An electric current is a flow of charged particles, such as electrons or ions, through an electrical conductor or space. It is defined as the net rate at which electric charge flows through a surface.12 The moving particles are called charge carriers, which may be of several types, depending on the conductor. In electric circuits, the charge carriers are often electrons moving through a wire. In semiconductors, the charge carriers can be electrons or holes. In an electrolyte, the charge carriers are ions, while in plasma - an ionized gas- they are also ions and electrons.3
In the International System of Units (SI), electric current is expressed in units of ampere (sometimes called an “amp”, symbol A), which is equivalent to one coulomb per second. The ampere is an SI base unit and electric current is a base quantity in the International System of Quantities (ISQ).4 Electric current is also known as amperage and is measured using a device called an ammeter.2
Electric currents create magnetic fields, which are used in motors, generators, inductors, and transformers. In ordinary conductors, they cause Joule heating, which creates light in incandescent light bulbs. Time-varying currents emit electromagnetic waves, which are used in telecommunications to broadcast information.
Printed 2026-06-28.
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Link to original Footnotes
Horowitz, Paul; Hill, Winfield (2015). The art of electronics (3rd ed.). Cambridge University Press. ISBN 978-0-521-80926-9. ↩
Walker, Jearl; Halliday, David; Resnick, Robert (2014). Fundamentals of physics (10th ed.). Hoboken, NJ: Wiley. ISBN 978-1118230732. OCLC 950235056. ↩ ↩2
Anthony C. Fischer-Cripps (2004). The electronics companion. CRC Press. p. 13. ISBN 978-0-7503-1012-3. ↩
The International System of Units (PDF), V4.01 (9th ed.), International Bureau of Weights and Measures, Jun 2026, ISBN 978-92-822-2272-0 ↩
Secondary
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