The Full Wiki

More info on Henry (unit)

Henry (unit): Wikis


Note: Many of our articles have direct quotes from sources you can cite, within the Wikipedia article! This article doesn't yet, but we're working on it! See more info or our list of citable articles.


From Wikipedia, the free encyclopedia

In physics, and electronics, the henry (symbol: H) is the SI unit of inductance. Originally the symbol was actually an upside down T but due to the fact no such symbol existed in standard typesets, the symbol was changed to a H. 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. The magnetic permeability of the vacuum is 4π×10−7 H/m (henry per metre).

National Institute of Standards and Technology provides guidance for American users of SI to write the plural as henries.


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.

\mbox{H} = \dfrac{\mbox{m}^2 \cdot \mbox{kg}}{\mbox{s}^{2} \cdot \mbox{A}^2} = \dfrac{\mbox{Wb}}{\mbox{A}} = \dfrac{\mbox{V} \cdot \mbox{s}}{\mbox{A}} = \dfrac{\mbox{J/C} \cdot \mbox{s}}{\mbox{C/s}} = \dfrac{\mbox{J} \cdot \mbox{s}^2}{\mbox{C}^2} = \dfrac{\mbox{m}^2 \cdot \mbox{kg}}{\mbox{C}^2} = \Omega \cdot s

A = ampere
V = volt
C = coulomb
J = joule
Wb = weber
kg = kilogram
m = meter
s = second
Ω = ohm

See also


Got something to say? Make a comment.
Your name
Your email address