Which statement describes alternating current?

• A. Current that flows in one direction only.
• B. Current that periodically reverses direction.
• C. Voltage that increases with time.
• D. A circuit with no load.

Answer: (B)

Alternating current is defined by its flow reversing direction at regular intervals. This is different from direct current, which keeps moving in one direction. In AC, the voltage and current typically vary over time in a repeating pattern, often a sine wave, so the direction of flow changes back and forth. This reversal is what distinguishes AC from the other ideas: one-direction flow describes direct current, a voltage that increases with time isn’t describing an alternating waveform, and a circuit with no load isn’t about the current’s direction at all.