Henry (unit): Difference between revisions
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[[Image:Inductor.jpg|thumb|150px|An [[inductor]].]] |
[[Image:Inductor.jpg|thumb|150px|An [[inductor]].]] |
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In [[physics]], and [[electronics]], the '''henry''' (symbol '''H''') is the [[SI derived unit]] of [[inductance]].<ref>{{cite web | title=How Many? A Dictionary of Units of Measurement | last=Rowlett | first = Russ | url = http://www.unc.edu/~rowlett/units/dictH.html | publisher = [[University of North Carolina at Chapel Hill]]}}</ref> It is named after [[Joseph Henry]] (1797–1878), the American scientist who discovered electromagnetic induction independently of and at about the same time as [[Michael Faraday]] (1791–1867) in England.<ref>{{cite web | title = A Princeton Companion | url = http://etcweb.princeton.edu/CampusWWW/Companion/henry_joseph.html | author = Herbert S. Bailey, Jr.}}</ref> The [[magnetic permeability]] of |
In [[physics]], and [[electronics]], the '''henry''' (symbol '''H''') is the [[SI derived unit]] of [[inductance]].<ref>{{cite web | title=How Many? A Dictionary of Units of Measurement | last=Rowlett | first = Russ | url = http://www.unc.edu/~rowlett/units/dictH.html | publisher = [[University of North Carolina at Chapel Hill]]}}</ref> It is named after [[Joseph Henry]] (1797–1878), the American scientist who discovered electromagnetic induction independently of and at about the same time as [[Michael Faraday]] (1791–1867) in England.<ref>{{cite web | title = A Princeton Companion | url = http://etcweb.princeton.edu/CampusWWW/Companion/henry_joseph.html | author = Herbert S. Bailey, Jr.}}</ref> The [[magnetic permeability]] of a vacuum is 4π×10<sup>−7</sup> H/m (henry per meter). |
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The [[National Institute of Standards and Technology]] provides guidance for American users of SI to write the plural as henries.<ref name=Taylor>{{Cite journal|author=Ambler Thompson & Barry N. Taylor|year=2008|url=http://physics.nist.gov/cuu/pdf/sp811.pdf|title=NIST Special Publication 811: Guide for the Use of the International System of Units (SI)|publisher=National Institute of Standards and Technology|accessdate=2013-03-21}} |
The [[National Institute of Standards and Technology]] provides guidance for American users of SI to write the plural as henries.<ref name=Taylor>{{Cite journal|author=Ambler Thompson & Barry N. Taylor|year=2008|url=http://physics.nist.gov/cuu/pdf/sp811.pdf|title=NIST Special Publication 811: Guide for the Use of the International System of Units (SI)|publisher=National Institute of Standards and Technology|accessdate=2013-03-21}} |
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Revision as of 19:42, 14 August 2013
In physics, and electronics, the henry (symbol H) is the SI derived unit of inductance.[1] It is named after Joseph Henry (1797–1878), the American scientist who discovered electromagnetic induction independently of and at about the same time as Michael Faraday (1791–1867) in England.[2] The magnetic permeability of a vacuum is 4π×10−7 H/m (henry per meter).
The National Institute of Standards and Technology provides guidance for American users of SI to write the plural as henries.[3]: 31
Definition
If the rate of change of current in a circuit is one ampere per second and the resulting electromotive force is one volt, then the inductance of the circuit is one henry. Other equivalent combinations of SI units are as follows:[4]
where
A = ampere,
C = coulomb,
F = farad,
J = joule,
kg = kilogram,
m = meter,
s = second,
Wb = weber,
V = volt,
Ω = ohm.
References
- ^ Rowlett, Russ. "How Many? A Dictionary of Units of Measurement". University of North Carolina at Chapel Hill.
- ^ Herbert S. Bailey, Jr. "A Princeton Companion".
- ^ Ambler Thompson & Barry N. Taylor (2008). "NIST Special Publication 811: Guide for the Use of the International System of Units (SI)" (PDF). National Institute of Standards and Technology. Retrieved 2013-03-21.
{{cite journal}}: Cite journal requires|journal=(help) - ^ "Essentials of the SI: Base & derived units". The NIST Reference on Constants, Units and Uncertainty. National Institute of Standards and Technology.
