Editing Magnetostriction (section)

{{Short description|Property of materials that causes them to change their shape during magnetization}}
'''Magnetostriction''' is a property of [[magnet|magnetic materials]] that causes them to change their shape or dimensions during the process of [[magnetization]]. The variation of materials' magnetization due to the applied [[magnetic field]] changes the magnetostrictive strain until reaching its saturation value, λ. The effect was first identified in 1842 by [[James Joule]] when observing a sample of [[iron]].<ref>
{{cite journal|title=On the Effects of Magnetism upon the Dimensions of Iron and Steel Bars|journal=The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science|date=1847|first=J.P.|last=Joule|volume= 30, Third Series|pages=76–87, 225–241|url=https://books.google.com/books?id=VEgEAAAAYAAJ&q=joule%20annals%20electricity%20219%201842&pg=PA76|access-date=2009-07-19 }} Joule observed in this paper that he first reported the measurements in a "conversazione" in Manchester, England, in {{Cite journal
  | last = Joule
  | first = James|title=On a new class of magnetic forces
  | journal = Annals of Electricity, Magnetism, and Chemistry
  | volume = 8
  | pages = 219–224
  | year = 1842
}}</ref>

Magnetostriction applies to magnetic fields, while [[electrostriction]] applies to electric fields.

Magnetostriction causes energy loss due to frictional heating in susceptible ferromagnetic cores, and is also responsible for the low-pitched humming sound that can be heard coming from transformers, where alternating currents produce a changing magnetic field.<ref>{{usurped|1=[https://web.archive.org/web/20191215204137/http://www.sctritonscience.com/Young/whytransformershum.htm Questions & answers on everyday scientific phenomena]}}. Sctritonscience.com. Retrieved on 2012-08-11.</ref>