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magnetic_flux_density [2020/05/13 14:29]
Dr Stan Zurek [Magnetic flux density]
magnetic_flux_density [2020/05/31 17:29] (current)
Dr Stan Zurek
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 **Magnetic flux density** $B$ - a physical quantity used as one of the basic measures of the intensity of [[magnetic field]].[(Mansfield>​[[http://​google.com/​books?​isbn=9780470746387|Michael Mansfield, Colm O'​Sullivan,​ Understanding Physics, John Wiley & Sons, 2010, ISBN 9780470746387,​ p. 413]])] The unit of magnetic flux density[(Jiles>​[[http://​google.com/​books?​isbn=9780412386404|David Jiles, Introduction to Magnetism and Magnetic Materials, Chapman and Hall, 1991, ISBN 9780412386404,​ p. 1-13]])] is //​**[[tesla]]**//​ or **T**. **Magnetic flux density** $B$ - a physical quantity used as one of the basic measures of the intensity of [[magnetic field]].[(Mansfield>​[[http://​google.com/​books?​isbn=9780470746387|Michael Mansfield, Colm O'​Sullivan,​ Understanding Physics, John Wiley & Sons, 2010, ISBN 9780470746387,​ p. 413]])] The unit of magnetic flux density[(Jiles>​[[http://​google.com/​books?​isbn=9780412386404|David Jiles, Introduction to Magnetism and Magnetic Materials, Chapman and Hall, 1991, ISBN 9780412386404,​ p. 1-13]])] is //​**[[tesla]]**//​ or **T**.
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 +[[Magnetic field strength]] $H$ can be thought of as excitation and the [[magnetic flux density]] $B$ as the response of the medium.
  
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 +Magnetic field is a [[vector field]] in space, and is a kind of [[energy]] whose full quantification requires the knowledge of the vector fields of both magnetic field strength $H$ and flux density $B$ (or other values correlated with them, like [[magnetisation]] or [[polarisation]]). In vacuum, at each point the $H$ and $B$ vectors are oriented along the same direction and are directly proportional through [[permeability]] of free space, but in other media they can be misaligned (especially in [[uniform material|non-uniform]] or [[anisotropy|anisotropic]] materials).
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 +The requirement of two quantities is analogous for example to [[electricity]]. Both [[electric voltage]] $V$ and [[electric current]] $I$ are required to fully quantify the effects of electricity,​ e.g. the amount of transferred energy.[(White>​[[http://​google.com/​books?​isbn=9781439866511|Mary Anne White, Physical Properties of Materials, Second Edition, CRC Press, 2011, ISBN 9781439866511,​ p. 359]])]
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 +The name //​**magnetic flux density**// and the symbol $B$ are defined by //​[[International Bureau of Weights and Measures]] (BIPM)// as a one of the [[coherent derived unit|coherent derived physical units]].[(BIPM>​[[http://​www.bipm.org/​en/​publications/​si-brochure/​section2-2.html|SI Brochure: The International System of Units (SI) [8th edition, 2006; updated in 2014], Section 2.2: SI derived units, {accessed 2016-06-15}]])] Therefore, strictly speaking, other names like //​**induction**//​ or //**B field**// which can be encountered in everyday technical jargon[(Mansfield)] are  incorrect.
  
 ===== Difficulty with definition ===== ===== Difficulty with definition =====
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 +It is difficult to give a concise definition of such a basic quantity like [[magnetic field]], but various authors give at least a descriptive version. The same applies to **magnetic flux density**, as well as the other basic quantity - **[[magnetic field strength]]**.
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 +The table below shows some examples of definitions of $H$ given in the literature (exact quotations are shown).
  
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magnetic_flux_density.1589372984.txt.gz ยท Last modified: 2020/05/13 14:29 by Dr Stan Zurek

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