Which type of current flows in one direction only?

Direct current is characterized by the flow of electric charge in one consistent direction. This unidirectional flow means that electrons move steadily from the negative terminal to the positive terminal of a power source, which is a fundamental property of direct current (DC).

This consistent flow allows direct current to be ideal for powering devices that require a stable voltage and current, such as batteries, electronic devices, and certain types of electric motors. The predictable nature of direct current simplifies circuit design for many applications.

In contrast, alternating current (AC) periodically reverses direction, while pulsating current varies in magnitude and may change direction but does not maintain a constant flow like DC. Bidirectional current typically implies a flow that alternates directions, which is also not the case for direct current. Thus, the defining characteristic of direct current is that it flows in one direction only, making it the correct choice in this context.