Flux

:This article is about the concept of flux in science and mathematics. For other uses of the word, see flux (disambiguation).

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For a physically flowing substance, the flux is the amount of that substance that flows through a given area of a surface in unit time.

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The flux density is the flux per unit area. It is a vector field describing the flow.

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More generally, for any vector field the 'flux' is defined in the same way as above, (as if it described a flow of an actual substance).

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