Divergence Theorem

${\iiint }_{\mathcal{W}}\text{div}(\vec{F})dV={\oint }_S\vec{F}\cdot d\vec{S}$

• Used in derivation of Gauss’s Law
• Like 3D version of Stoke’s Theorem, where $S$ is a positively oriented boundary of $W$. That essentially means the normal of $S$ points outward.