Final answer:
An electrical current that changes direction every half cycle is known as alternating current (AC), different from direct current (DC) which flows in one direction only.
Step-by-step explanation:
An electrical current that flows in one direction (+) for a half cycle and then in the other direction (-) for a half cycle is known as alternating current (AC). Direct current (DC) is the flow of electric charge in only one direction, while alternating current is the flow of electric charge that periodically reverses direction. Alternating current is what powers our homes and businesses, and it changes direction at regular time intervals, unlike direct current, which has a fixed magnitude and direction.