Editing Transformer (section)

{{Short description|Device to couple energy between circuits}}
{{about|the electrical device|other uses}}
{{Infobox electronic component 
| name              = Transformer
| image             = Philips_N4422_-_power_supply_transformer-2098.jpg
| image_size        = 200px
| caption           = An O-core transformer consisting of two coils of copper wire wrapped around a magnetic core
| type              = [[Passivity (engineering)|Passive]]
| working_principle = [[Electromagnetic induction]]
| inventor          = [[Michael Faraday]]<ref name="IEEUK">{{cite web|url=http://www.theiet.org/resources/library/archives/biographies/faraday.cfm|title=Archives Michael Faraday biography – The IET|website=theiet.org}}</ref>
| invention_Year    = 1831
| symbol            = [[File:Transformer Iron Core.svg|50px]]
}}

In [[electrical engineering]], a '''transformer''' is a [[passive component]] that transfers [[electrical energy]] from one electrical circuit to another circuit, or multiple [[Electrical network|circuits]]. A varying current in any coil of the transformer produces a varying [[magnetic flux]] in the transformer's core, which induces a varying [[electromotive force|electromotive force (EMF)]] across any other coils wound around the same core. Electrical energy can be transferred between separate coils without a metallic (conductive) connection between the two circuits. [[Faraday's law of induction]], discovered in 1831, describes the induced voltage effect in any coil due to a changing magnetic flux encircled by the coil.

Transformers are used to change [[Alternating current|AC]] voltage levels, such transformers being termed step-up or step-down type to increase or decrease voltage level, respectively. Transformers can also be used to provide [[galvanic isolation]] between circuits as well as to couple stages of signal-processing circuits. Since the invention of the first [[constant-potential transformer]] in 1885, transformers have become essential for the [[electric power transmission|transmission]], [[electric power distribution|distribution]], and utilization of alternating current electric power.<ref name="Bedell (1942)">{{cite journal|last1=Bedell|first1=Frederick|title=History of A-C Wave Form, Its Determination and Standardization|journal=Transactions of the American Institute of Electrical Engineers|volume=61|issue=12|page=864|doi=10.1109/T-AIEE.1942.5058456|year=1942|s2cid=51658522}}</ref> A wide range of transformer designs is encountered in electronic and electric power applications. Transformers range in size from [[Radio Frequency|RF]] transformers less than a cubic centimeter in volume, to units weighing hundreds of tons used to interconnect the [[power grid]].
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