The difference in electrical potential between two points is defined as

• A. Voltage
• B. Current
• C. Resistance
• D. Reactance

Answer: (A)

Voltage is the difference in electrical potential between two points. It represents the potential energy per unit charge that can push charges to move, and it drives current when a complete path exists. Measured in volts, this potential difference is what a battery or power source provides to a circuit. Current, in contrast, is the rate at which charge actually flows; resistance is how much a component opposes that flow; and reactance is the frequency-dependent opposition in AC circuits due to energy storage in capacitors or inductors. For example, a 9-volt source across a lamp creates a 9 V potential difference, and the resulting current depends on the lamp’s resistance.