Series-Parallel Circuits

In actual use, most circuits are a combination of the two types. These circuits are known as series-parallel circuits.

At least three resistors are needed to construct a series-parallel circuit. Why is this true? The explanation is simple.

A circuit with only one resistor must be a series circuit, because the current can only flow in one path. A circuit with two resistors can be either a series circuit or a parallel circuit, but not both.

A good example of a series-parallel circuit is presented in Figure 2.18.

Figure 2.18

In this illustration, resistor R₁ is in series with a parallel combination of R₂ and R₃. This is a simple series-parallel circuit.