Current Direction
In the early days of electricity, it was believed that current was a movement
of positive charge and that these charges moved around the circuit from the
positive terminal of the battery to the negative as depicted in Figure 2–11(a).
Based on this, all the laws, formulas, and symbols of circuit theory were
developed. (We now refer to this direction as the conventional current
direction.) After the discovery of the atomic nature of matter, it was learned
that what actually moves in metallic conductors are electrons and that they
move through the circuit as in Figure 2–11(b). This direction is called the
electron flow direction. However, because the conventional current direction
was so well established, most users stayed with it. We do likewise. Thus,
in this book, the conventional direction for current is used.