This document discusses several topics related to steady electric currents: - It defines different types of electric currents including conduction, electrolytic, convection, and displacement currents. - It introduces current density and derives Ohm's law, relating current density to electric field and conductivity. - It describes electromotive force (EMF) as the driving force provided by sources like batteries to maintain steady current in closed circuits, as stated by Kirchhoff's voltage law. - It introduces the continuity equation relating divergence of current density to charge density changes, and derives Kirchhoff's current law equating the sum of currents at junctions to zero.