Editing Electric current (section)

== Alternating and direct current <span class="anchor" id="AC and DC"></span> ==
{{See also|War of the currents}}

In [[alternating current]] (AC) systems, the movement of [[electric charge]] periodically reverses direction. AC is the form of [[electric power]] most commonly delivered to businesses and residences. The usual [[waveform]] of an [[AC power]] circuit is a [[sine wave]], though certain applications use alternative waveforms, such as [[Triangle wave|triangular]] or [[Square wave (waveform)|square wave]]s. [[Audio frequency|Audio]] and [[Radio frequency|radio]] signals carried on electrical wires are also examples of alternating current. An important goal in these applications is recovery of information encoded (or ''[[modulated]]'') onto the AC signal.

In contrast, [[direct current]] (DC) refers to a system in which the movement of electric charge in only one direction (sometimes called unidirectional flow). Direct current is produced by sources such as [[battery (electrical)|batteries]], [[thermocouple]]s, [[solar cell]]s, and [[commutator (electric)|commutator]]-type electric machines of the [[dynamo]] type. Alternating current can also be converted to direct current through use of a [[rectifier]]. Direct current may flow in a [[conductor (material)|conductor]] such as a wire, but can also flow through [[semiconductor]]s, [[electrical insulation|insulators]], or even through a [[vacuum]] as in [[electron beam|electron or ion beams]]. An [[archaism|old name]] for direct current was ''galvanic current''.<ref>{{cite book |title=Clinical Electrophysiology: Electrotherapy and Electrophysiologic Testing |author1=Andrew J. Robinson |author2=Lynn Snyder-Mackler |edition=3rd|year=2007 |publisher= Lippincott Williams & Wilkins|isbn= 978-0-7817-4484-3|page=10|url=https://books.google.com/books?id=C2-9bcIjPBsC&q=%22galvanic+current%22+%22direct+current%22&pg=PA10}}</ref>