In the preceding chapter we examined series circuits, starting with series configurations of resistors and voltage sources. In this chapter we shall examine the “mirror twin” of series circuits, namely parallel circuits. Again, we shall begin by defining the parallel configuration, and explore how to combine sources and resistors in parallel. From there we shall introduce new laws and rules unique to parallel configurations. For everything said about series circuits, there are corresponding statements regarding parallel circuits. Just as there were specific laws and techniques useful in the series case, such as Kirchhoff's voltage law and the voltage divider rule, there are corresponding laws and techniques useful in the series case (e.g., Kirchhoff's current law and the current divider rule).

A parallel circuit may contain any number of resistors and current sources, or in place of the current sources, a single voltage source. We shall examine how to determine the current flow through each component, the voltage across each component and the power either dissipated or generated by each component. As usual, other practical issues will also be examined along with appropriate computer simulations.

Parallel circuits are in many ways the complement of series circuits. The hallmark of a series connection is that all components in that connection see the same current. Similarly, the most notable characteristic of a parallel connection is that all components see the same voltage. This implies that parallel connections have only two nodes, or two points of connection upon which everything is connected. Just as a series connection can be envisioned as a sort of chain with every element a link in that chain, a parallel connection can be envisioned as a sort of ladder with every element a rung on that ladder.