Editing Electromagnetic coil (section)

==Windings and taps==
[[File:Transformers.png|thumb|Diagram of typical transformer configurations]]
The wire or conductor which constitutes the coil is called the '''winding'''.<ref name="google2">{{cite book|title=NFPA's Pocket Dictionary of Electrical Terms|author=Stauffer, H.B.|date=2005|publisher=Jones & Bartlett Learning, LLC|isbn=9780877655992|url=https://books.google.com/books?id=9sW_knz5P0wC&pg=PA273|page=273|access-date=2017-01-07}}</ref>  The hole in the center of the coil is called the '''core''' area or ''magnetic axis''.<ref name="Amos">{{cite book
  | last = Amos
  | first = S W 
  |author2=Roger Amos
  | title = Newnes Dictionary of Electronics 
  | publisher = Newnes 
  | year = 2002
  | page = 191
  | url = https://books.google.com/books?id=lROa-MpIrucC&dq=magnetic+core&pg=PA191
  | isbn = 978-0080524054}}</ref>  Each loop of wire is called a  '''turn'''.<ref name="Laplante" />  In windings in which the turns touch, the wire must be insulated with a coating of nonconductive [[insulation (electric)|insulation]] such as plastic or [[magnetic wire|enamel]] to prevent the current from passing between the wire turns. The winding is often wrapped around a ''coil form'' made of plastic or other material to hold it in place.<ref name="Laplante" />  The ends of the wire are brought out and attached to an external circuit. Windings may have additional electrical connections along their length; these are called '''taps'''.<ref name="google3">{{cite book|title=Comprehensive Dictionary of Electrical Engineering|author=Laplante, P.A.|date=1999|publisher=Springer Berlin Heidelberg|isbn=9783540648352|url=https://books.google.com/books?id=soSsLATmZnkC&pg=PA633|page=633|access-date=2017-01-07}}</ref>  A winding that has a single tap in the center of its length is called '''center-tapped'''.<ref name="google4">{{cite book|title=NFPA's Pocket Dictionary of Electrical Terms|author=Stauffer, H.B.|date=2005|publisher=Jones & Bartlett Learning, LLC|isbn=9780877655992|url=https://books.google.com/books?id=9sW_knz5P0wC&pg=PA29|page=29|access-date=2017-01-07}}</ref>

Coils can have more than one winding, insulated electrically from each other. When there are two or more windings around a common magnetic axis, the windings are said to be '''inductively coupled''' or '''magnetically coupled'''.<ref name="google5">{{cite book|title=Newnes Dictionary of Electronics|author1=Amos, S.W.|author2=Amos, R.|date=2002|publisher=Elsevier Science|isbn=9780080524054|url=https://books.google.com/books?id=lROa-MpIrucC&pg=PA167|page=167|access-date=2017-01-07}}</ref>  A time-varying current through one winding will create a time-varying magnetic field that passes through the other winding, which will induce a time-varying voltage in the other windings. This is called a [[transformer]].<ref name="google6">{{cite book|title=Newnes Dictionary of Electronics|author1=Amos, S.W.|author2=Amos, R.|date=2002|publisher=Elsevier Science|isbn=9780080524054|url=https://books.google.com/books?id=lROa-MpIrucC&pg=PA326|page=326|access-date=2017-01-07}}</ref>  The winding to which current is applied, which creates the magnetic field, is called the ''[[primary winding]]''. The other windings are called ''[[secondary winding]]s''.