What is the key difference between alternating current (AC) and direct current (DC) in terms of current direction?

What is the key difference between alternating current (AC) and direct current (DC) in terms of current direction?

• A. DC flows in a constant direction; AC periodically reverses direction.
• B. AC flows in a constant direction; DC periodically reverses direction.
• C. Both always flow in the same direction.
• D. Current direction is irrelevant for AC vs DC.

Answer: (A)

The main point is how the current direction behaves over time. In direct current, the flow of charge stays in a single direction through the circuit (the magnitude can vary, but the direction does not change). In alternating current, the direction reverses repeatedly, meaning the current flows first one way and then the opposite way in cycles (for household power, these reversals happen many times per second). This difference in direction behavior is why direct current is described as unidirectional and alternating current as bidirectional over time.

The main point is how the current direction behaves over time. In direct current, the flow of charge stays in a single direction through the circuit (the magnitude can vary, but the direction does not change). In alternating current, the direction reverses repeatedly, meaning the current flows first one way and then the opposite way in cycles (for household power, these reversals happen many times per second). This difference in direction behavior is why direct current is described as unidirectional and alternating current as bidirectional over time.