Electromagnetic tensor

Summary

The electromagnetic tensor, or field strength tensor, is an antisymmetric tensor field of rank two on spacetime. It combines the electric field and the magnetic field into one object. Under a Lorentz transformation it transforms as a tensor, which explains how electric and magnetic fields mix for moving observers. In terms of it, Maxwell's equations become two short tensor equations. In the language of differential forms it is a closed $2$-form, the curvature of the electromagnetic potential.