2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/33831We complete a metric-free axiomatic framework for electrodynamics by introducing the appropriate energy-momentum current Sigma of the electromagnetic field. We start from the Lorentz force density and motivate the form of Sigma. Then we postulate it (fourth axiom) and discuss its properties. In particular, it is found that Sigma is traceless and invariant under an electric-magnetic reciprocity transformation. By using the Maxwell-Lorentz spacetime relation (fifth axiom), Sigma is also shown to be symmetric, that is, it has 9 independent components25 pages, Revtex, Dedicated to the memory of our friend and colleague Ruggiero de Ritis from NapoliGeneral Relativity and Quantum CosmologyHigh Energy Physics - TheoryClassical Physicstext