• $\vec E$ electric field
• $\vec B$ magnetic field
• $q$ electric charge
• $\vec A(\vec r')$ magnetic vector potential
• $V(\vec r)$ potential
• $\Phi$ flux
• $Q$ net charge
• $\lambda (\vec r')$ line charge
• $\sigma(\vec r')$ surface charge
• $\rho(\vec r')$ volume charge
• $\vec j(\vec r')$ current density
• $I$ current
• $\vec S$ energy flux density (Poynting vector)
• $u$ energy density in the fields
• $\beta$ relativity factor $\frac vc$
• $\vec m$ magnetic dipole moment

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• $g^{\mu \nu}$ metric tensor
• $\Lambda^\mu_\nu$ Minkowski metric
• $u^\mu$ 4-vector velocity