Weber (unit): Difference between revisions
imported>Paul Wormer |
imported>Paul Wormer No edit summary |
||
| Line 1: | Line 1: | ||
{{subpages}} | {{subpages}} | ||
The ''' | The '''weber''' (symbol Wb) is the [[SI]] unit of [[magnetic flux]]. It is named for the German physicist [[Wilhelm Eduard Weber]]. | ||
The ninth CGPM (''Conférence Générale des Poids et Mesures'', General Conference on Weights and Measures) ratified in 1948 a definition based on [[Faraday's law (electromagnetism)|Faraday's law]] for magnetic induction. This law connects electromotive force <math>\scriptstyle \mathcal{E}</math>, (in volt), to the rate of change of magnetic flux Φ (in Wb/s) | The ninth CGPM (''Conférence Générale des Poids et Mesures'', General Conference on Weights and Measures) ratified in 1948 a definition based on [[Faraday's law (electromagnetism)|Faraday's law]] for magnetic induction. This law connects electromotive force <math>\scriptstyle \mathcal{E}</math>, (in volt), to the rate of change of magnetic flux Φ (in Wb/s). | ||
:<math> | :<math> | ||
\mathcal{E} = -\frac{d\Phi}{dt} | \mathcal{E} = -\frac{d\Phi}{dt} | ||
</math> | </math> | ||
If Φ is linear in time—then Φ changes with a uniform rate in time—and if Φ = 0 at ''t'' = 0, then | |||
:<math> | |||
\Phi(t) = - t\, \mathcal{E} | |||
</math> | |||
This equation forms the basis of the formal definition, wich reads: | |||
''One weber is the magnetic flux which, linking a circuit of one turn, would produce in it an electromotive force of 1 volt if it were reduced to zero at a uniform rate in 1 second.'' (Resolution 2, International Committee for Weights and Measures. 1946)<ref> | |||
[http://www.bipm.org/utils/common/pdf/si_brochure_8_en.pdf BIPM brochure about SI]. PDF page 52; paper page 144.</ref> | [http://www.bipm.org/utils/common/pdf/si_brochure_8_en.pdf BIPM brochure about SI]. PDF page 52; paper page 144.</ref> | ||
| Line 15: | Line 20: | ||
<references /> | <references /> | ||
==External link== | ==External link== | ||
[http://www.sizes.com/units/weber.htm sizes.com] | [http://www.sizes.com/units/weber.htm weber at sizes.com] | ||
Revision as of 05:03, 25 June 2008
The weber (symbol Wb) is the SI unit of magnetic flux. It is named for the German physicist Wilhelm Eduard Weber.
The ninth CGPM (Conférence Générale des Poids et Mesures, General Conference on Weights and Measures) ratified in 1948 a definition based on Faraday's law for magnetic induction. This law connects electromotive force , (in volt), to the rate of change of magnetic flux Φ (in Wb/s).
If Φ is linear in time—then Φ changes with a uniform rate in time—and if Φ = 0 at t = 0, then
This equation forms the basis of the formal definition, wich reads: One weber is the magnetic flux which, linking a circuit of one turn, would produce in it an electromotive force of 1 volt if it were reduced to zero at a uniform rate in 1 second. (Resolution 2, International Committee for Weights and Measures. 1946)[1]
Wb = V⋅s = N⋅m⋅A−1 = kg⋅A−1⋅s−2⋅m2 = T⋅m2, where A stands for ampere, T for tesla, V for volt, and N for newton.
Reference
- ↑ BIPM brochure about SI. PDF page 52; paper page 144.