Which component is known for allowing current to flow only in one direction?

The component that allows current to flow only in one direction is the diode. Diodes are semiconductor devices that have two terminals, typically referred to as the anode and cathode. When a positive voltage is applied to the anode relative to the cathode, the diode becomes forward-biased, allowing current to flow through it. However, if the polarity is reversed, the diode becomes reverse-biased, effectively blocking current flow. This property makes diodes essential in various applications, such as rectifiers in power supplies, where they convert alternating current (AC) to direct current (DC).

On the other hand, transistors are used for signal amplification and switching rather than for directing current flow in a single direction. Capacitors store and release electrical energy but do not control the direction of current flow. Resistors limit current flow and drop voltage but do not provide directional control. Therefore, the unique ability of diodes to permit current flow in only one direction is key to their role in electronic circuits.