Flux
= Flux
{wiki}
A flux records transport of a quantity through a surface per unit time. A flux density $\mathbf j$ gives total transport rate $\int_S\mathbf j\cdot\mathbf n\,dS$, where $\mathbf n$ is the unit <normal vector>. A <conservation law> relates its <divergence> to the local change in the quantity's density.