Electric circuits often contain several resistors connected in various ways. In this section we consider simple circuits containing resistors and batteries. For each type of circuit, you’ll learn how to calculate the net effect of a group of resistors.

Key Terms

• series circuit
• parallel circuit
• Ammeter
• Voltmeter

Direct current (DC) circuits

A simple DC circuit consists of a source of potential difference, such as a battery, a resistor or load (such as a bulb), switch, and wire. An electric circuit is a complete path through which charges can flow. A schematic diagram for a circuit is sometimes called a circuit diagram.

Note: Batteries produce direct currents (DC).

In the circuit diagram shown in Figure 13, electrons flow from the negative terminal of the battery to the positive terminal. The direction of the current, I, is just the opposite: from the positive terminal to the negative terminal.