Terminals and Ports

This article presents some basic concepts for electrical circuits. A port is defined as a set of terminals that satisfies the port-Kirchhoff current law. Transfer of energy occurs when a set of terminals forms a port. For a connected RLC circuit the only port is the one that consists of all the terminals. It is explained that in order to formalize the architecture of an electrical circuit it is convenient to use a digraph with leaves. The leaves correspond to the external terminals of a circuit, the edges to the circuit elements, and the vertices to the connections.