Ampere's law

<math>\oint_S \mathbf{B} \cdot d\mathbf{s} = \mu_0 I </math>

B is the magnetic flux

s is an infinitesimal element of the closed loop S

I is the current encircled by the curve S

μ₀ is the permeability of free space

<math>\oint_S</math> is the path integral along the loop S

This law, as the others laws of electromagnetism was later incorperated into Maxwell's equations, unifying all of electromagnetism.