ABSTRACT
So far, we have dealt with electrostatic fields, namely, the fields associated with time-invariant charges at rest. We now consider the charges in an organized macroscopic motion, which constitute an electric current. Our focus in this chapter is on the steady flow of free charges in conducting materials, i.e., on steady (timeinvariant) electric currents, whose macroscopic characteristics (like the amount of current through a wire conductor) do not vary with time. Steady currents are also called direct currents, abbreviated dc.
