DC CIRCUIT ANALYSIS
Basic DC Theory
The first step is to draw an assumed direction of current flow (Figure 38). It does not matter
whether the direction is correct. If it is wrong, the resulting value for current will be negative.
Second, mark the polarity of voltage across each component (Figure 39). It is necessary to
Figure 38 Assumed Direction of Current Flow
choose a direction for current through the center leg, but it is not necessary to put in a new
variable. It is simply I2 - I1.
Figure 39 Marking Polarity