A potential difference is needed to cause electric current to flow through a resistor. The greater the resistance, the greater the required potential difference. Wires come in a variety of shapes, sizes, and lengths. In addition, they can be made from different metals and operate over a wide range of temperatures. In this section, you will study the relationships between voltage, current, and resistance in simple circuits and the factors that affect the resistance of a conductor (wire).

Key Terms

• Ohm’s law
• ohmic and non-ohmic
• resistance
• resistivity