Editing Magnetism (section)

== Electromagnet ==
[[File:Electromagnet.gif|thumb|upright=1.2|An electromagnet attracts paper clips when current is applied, creating a magnetic field. The electromagnet loses them when current and magnetic field are removed.]]

An [[electromagnet]] is a type of [[magnet]] in which the [[magnetic field]] is produced by an [[electric current]].<ref>{{harvnb|Purcell|2012|p=320,584}}</ref> The magnetic field disappears when the current is turned off. Electromagnets usually consist of a large number of closely spaced turns of wire that create the magnetic field. The wire turns are often wound around a [[magnetic core]] made from a [[ferromagnetic]] or [[ferrimagnetic]] material such as [[iron]]; the magnetic core concentrates the [[magnetic flux]] and makes a more powerful magnet.

The main advantage of an electromagnet over a [[permanent magnet]] is that the magnetic field can be quickly changed by controlling the amount of electric current in the winding. However, unlike a permanent magnet that needs no power, an electromagnet requires a continuous supply of current to maintain the magnetic field.

Electromagnets are widely used as components of other electrical devices, such as [[electric motor|motors]], [[Electric generator|generators]], [[relay]]s, solenoids, [[loudspeaker]]s, [[hard disk]]s, [[Magnetic resonance imaging|MRI machines]], scientific instruments, and [[magnetic separation]] equipment. Electromagnets are also employed in industry for picking up and moving heavy iron objects such as scrap iron and steel.<ref name="Merzouki">
{{cite book
 | last1  = Merzouki | first1 = Rochdi
 | last2  =  Samantaray | first2 = Arun Kumar
 | last3  = Pathak | first3 = Pushparaj Mani
 | title  = Intelligent Mechatronic Systems: Modeling, Control and Diagnosis
 | publisher = Springer Science & Business Media
 | date   = 2012
 | pages  = 403–405
 | url    = https://books.google.com/books?id=k81ECeMxyk8C&q=ferromagnetic+electromagnet&pg=PA404
 | isbn   = 978-1447146285
}}</ref> Electromagnetism was discovered in 1820.<ref>
{{cite journal
 | last = Sturgeon
 | first = W.
 | title = Improved Electro Magnetic Apparatus
 | journal = Trans. Royal Society of Arts, Manufactures, & Commerce
 | volume = 43
 | pages = 37–52
 | year = 1825
}} cited in
{{cite book
 | last = Miller
 | first = T.J.E
 | title = Electronic Control of Switched Reluctance Machines
 | publisher = Newnes
 | year = 2001
 | pages = 7
 | url = https://books.google.com/books?id=E8VroIWyjB8C&pg=PA7
 | isbn = 978-0-7506-5073-1
}}</ref>