Direct Current Circuits I
Figure 3.1 shows a sketch of the simplest circuit showing the physical details: a battery, a resistor, and connecting wires. As you study circuits, you will need an easy way to communicate the electrical nature of a circuit without describing unnecessary details, such as the color, size, or shape of the components. You can do this by means of a circuit schematic, a sort of shorthand drawing. Figure 3.2 shows a schematic of the circuit in Figure 3.1. In the figure, you will note the special symbols used to represent the battery (a series of alternately long and short line segments) and the resistor (a jagged line). Also, note that the long lines connecting these components represent wires to carry the current. The positive terminal of the battery can be identified as the one emerging from a longer line segment (labeled with a plus sign in the figure), while the negative terminal comes from one of the shorter line segments.