In general a circuit may have resistances in series, in parallel, or both series and parallel.

**Resistors in Series **

**Resistors in Parallel **

The total resistance R is given by

**Combinations of Resistors in Series and Parallel **

The diagram below contains two parallel networks in series. We calculate the resistance of each parallel network and add them together like resistors in series.

The resistance of the first network below was found above:

The total resistance in the circuit is then

For the second circuit:

We now have two sets of series resistors in parallel. The circuit above is equivalent to having two resistances of

andin parallel.