Determining the Total Resistance

A more quantitative example for determining total resistance and the current in each branch in a combination circuit is shown in the following example. Also refer to Figure 96.

The first step is to determine the current at junction A, leading into the parallel branch. To determine the IT, the total resistance RT of the entire circuit must be known. The total resistance of the circuit is given as:

With the total resistance RT now determined, the total IT can be determined. Using Ohm’s law:

The current through the parallel branches of R2 and R3 can be determined using the current divider rule discussed earlier in the text. Recall that:

Now using Kirchhoff’s current law, the current in branch with R3 can be determined.