The Tesla reference article from the English Wikipedia on 24-Jul-2004
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Tesla

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The tesla (symbol T) is the compound derived SI unit of magnetic flux density or magnetic inductivity. At the Conference General des Poids et Mesures (CGPM) in Paris in 1960, the unit was named in honor of the Serbian-American inventor and electrical engineer Nikola Tesla who made several important contributions to the field of electromagnetism.

1 T = 1 V · s · m -2 = 1 kg · s -2 · A -1 = 1 N · A -1 m -1 = 1 Wb · m -2

A smaller derived unit, the gauss = 10-4 T, was once used.

Geophysics uses a unit of 1 γ = 10 -9 T.