Encyclopedia Magnetica

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magnetic_permeability

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magnetic_permeability [2016/02/23 01:37]
Dr Stan Zurek
magnetic_permeability [2019/06/03 18:29] (current)
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-| //​[[user/​Stan Zurek]], Magnetic permeability,​ [[http://​Encyclopedia-Magnetica.com|Encyclopedia-Magnetica.com]],​ {accessed on @YEAR@-@MONTH@-@DAY@}// | +| //​[[user/​Stan Zurek]], ​**[[Magnetic permeability]]**, [[http://​Encyclopedia-Magnetica.com|Encyclopedia-Magnetica.com]],​ {accessed on @YEAR@-@MONTH@-@DAY@}//​ |
-| //​[[/​wiki/​awaiting review]] ​// |+
  
-{{page>insert/todo}}+**Magnetic permeability**,​ denoted by **μ** - a property of a given medium quantifying its magnetic response of [[flux density]] $B$  when subjected to [[magnetic field strength]] $H$.[(Jiles>[[http://​google.com/​books?​isbn=9781482238884|David Jiles, Introduction to Magnetism and Magnetic Materials, Third Edition, CRC Press, 2015, ISBN 9781482238884,​ p. 11]])] ​
  
-**Magnetic ​permeability** +<box 30% right #​f0f0f0>​ 
 +Permeabilities of [[magnetic material|magnetic materials]] (e.g. [[ferromagnets]]) are much higher than those of [[non-magnetic material|non-magnetic materials]] (e.g. [[permeability ​of free space|vacuum]],​ [[diamagnets]] and [[paramagnets]]) 
 +[[file/​permeabilities_-_magnetica.png|{{permeabilities_-_magnetica.png}}]] 
 +{{page>​insert/​by_SZ}} 
 +</​box>​ 
 + 
 +[[Permeability of free space]] (or vacuum) is a universal physical constant defined in the [[international system of units]] (SI) denoted as $μ_0$ and its value defined exactly[(Jiles)][(BIPM_mu0>​[[http://​www.bipm.org/​en/​publications/​si-brochure/​ampere.html|Unit of electric current (ampere), SI Brochure: The International System of Units (SI) [8th edition, 2006; updated in 2014]], {accessed 2016-06-27})] as $μ_0 = 4 × π × 10^{-7}$ [[henry]] per [[metre]] which is approximately $μ_0 \approx 1.2566 × 10^{-6}$ H/m. 
 + 
 +The term "​name"​ was proposed in 1885 by Olivier Heaviside. 
 + 
 +===== Practical significance of permeability ===== 
 +From a practical viewpoint permeability is one of the basic parameters which allows categorising all materials as "​[[magnetic material|magnetic]]"​ (permeability much greater than that of vacuum $μ >> μ_0$) and "​[[non-magnetic material|non-magnetic]]"​ (permeability similar to that of vacuum $μ \approx μ_0$). In reality all materials are magnetic because they always exhibit some magnetic response to the magnetic excitation so that: 
 + 
 +|  (1)  |  $$B = μ · H$$  |  (T)  | 
 + 
 +[[Ferromagnet|Ferromagnetic]] and [[ferrimagnet|ferrimagnetic]] materials have their permeabilities significantly greater than vacuum and are used for construction of [[magnetic core|magnetic cores]] in [[magnetic circuit|magnetic circuits]]. 
 + 
 +However, at sufficiently high excitation all magnetic materials exhibit [[magnetic saturation]],​ with which the permeability reduces to that of vacuum. 
 + 
 +<box 30% right #​f0f0f0>​ 
 +Permeability of [[ferromagnetic material|ferromagnetic materials]] is a non-linear function of the applied excitation and reduces when approaching saturation 
 +[[file/​permeability_of_ferromagnet_-_magnetica.png|{{permeability_of_ferromagnet_-_magnetica.png}}]] 
 +{{page>​insert/​by_SZ}} 
 +</​box>​ 
 + 
 + 
 + 
 +===== Types of permeability =====
  
 There are several types of magnetic permeability:​ There are several types of magnetic permeability:​
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   * [[effective permeability]]   * [[effective permeability]]
   * [[equivalent permeability]]   * [[equivalent permeability]]
 +  * [[free space permeability]]
   * [[ideal permeability]]   * [[ideal permeability]]
   * [[imaginary permeability]]   * [[imaginary permeability]]
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   * [[initial permeability]]   * [[initial permeability]]
   * [[intrinsic permeability]]   * [[intrinsic permeability]]
 +  * [[linear permeability]]
   * [[magnetic constant]]   * [[magnetic constant]]
   * [[maximum permeability]]   * [[maximum permeability]]
   * [[non-linear permeability]]   * [[non-linear permeability]]
   * [[peak permeability]]   * [[peak permeability]]
-  * [[permeability of free space]] (or vacuum) 
   * [[post-saturation permeability]]   * [[post-saturation permeability]]
   * [[pulse permeability]]   * [[pulse permeability]]
   * [[quasi-permeability]]   * [[quasi-permeability]]
 +  * [[quasi-static permeability]]
   * [[real permeability]]   * [[real permeability]]
   * [[recoil permeability]]   * [[recoil permeability]]
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   * [[scalar permeability]]   * [[scalar permeability]]
   * [[tensor permeability]]   * [[tensor permeability]]
 +  * [[universal magnetic constant]]
 +  * [[vacuum permeability]]
   * [[vector permeability]]   * [[vector permeability]]
  
magnetic_permeability.txt · Last modified: 2019/06/03 18:29 (external edit)

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