Editing Inductor (section)

==Inductor construction==
{{multiple image
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| image1   = Common mode choke 2A with 20mH inductance.jpg
| caption1 = A ferrite core inductor with two 20&nbsp;mH windings.
| image2   = Ferrite bead no shell.jpg
| caption2 = A [[ferrite bead|ferrite "bead"]] [[choke (electronics)|choke]], consisting of an encircling [[ferrite (magnet)|ferrite]] cylinder, suppresses electronic noise in a computer power cord.
| image3   = Drosselspule im Umspannwerk Bisamberg.jpg
| caption3 = Large 50 [[volt-ampere reactive|Mvar]] [[three-phase electric power|three-phase]] iron-core loading inductor at a utility substation
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An inductor usually consists of a coil of conducting material, typically insulated [[Copper wire and cable|copper wire]], wrapped around a [[magnetic core|core]] either of plastic (to create an air-core inductor) or of a [[ferromagnetic]] (or [[Ferrimagnetism|ferrimagnetic]]) material; the latter is called an "iron core" inductor. The high [[Permeability (electromagnetism)|permeability]] of the ferromagnetic core increases the magnetic field and confines it closely to the inductor, thereby increasing the inductance. Low frequency inductors are constructed like transformers, with cores of [[electrical steel]] [[laminate]]d to prevent [[eddy current]]s. 'Soft' [[ferrite (magnet)|ferrites]] are widely used for cores above [[audio frequency|audio frequencies]], since they do not cause the large energy losses at high frequencies that ordinary iron alloys do. Inductors come in many shapes.  Some inductors have an adjustable core, which enables changing of the inductance. Inductors used to block very high frequencies are sometimes made by stringing a ferrite bead on a wire.

Small inductors can be etched directly onto a [[printed circuit board]] by laying out the trace in a [[spiral]] pattern. Some such planar inductors use a [[magnetic core#Planar core|planar core]].  Small value inductors can also be built on [[integrated circuit]]s using the same processes that are used to make [[Interconnects (integrated circuits)|interconnect]]s. [[Aluminium interconnect]] is typically used, laid out in a spiral coil pattern. However, the small dimensions limit the inductance, and it is far more common to use a circuit called a ''[[gyrator]]'' that uses a [[capacitor]] and active components to behave similarly to an inductor. Regardless of the design, because of the low inductances and low power dissipation on-die inductors allow, they are currently only commercially used for high frequency RF circuits.
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===Shielded inductors===
Inductors used in power regulation systems, lighting, and other systems that require low-noise operating conditions, are often partially or fully shielded.<ref name="Ott">{{cite book
 | last1  = Ott
 | first1 = Henry W.
 | title  = Electromagnetic Compatibility Engineering
 | publisher = John Wiley and Sons
 | date   = 2011
 | pages  = 203
 | url    = https://books.google.com/books?id=2-4WJKxzzigC&q=shielding+transformer+inductor&pg=PA203
 | isbn   = 978-1118210659
 }}</ref><ref name="Violette">{{cite book
 | last1  = Violette
 | first1 = Norman 
 | title  = Electromagnetic Compatibility Handbook
 | publisher = Springer
 | date   = 2013
 | pages  = 515–516
 | url    = https://books.google.com/books?id=K7_nCAAAQBAJ&q=shielding+transformer+inductor&pg=PA516
 | isbn   = 978-9401771443
 }}</ref> In [[telecommunication circuit]]s employing induction coils and repeating transformers shielding of inductors in close proximity reduces circuit cross-talk.