ABYC Marine Electrical Practice Exam

Which device allows current to flow in one direction only?

1. Transistor

2. Inductor

3. Diode

4. Resistor

The correct answer is: Diode

The correct answer is that a diode allows current to flow in one direction only. Diodes are semiconductor devices that function as one-way valves for electric current, permitting it to flow from the anode (positive side) to the cathode (negative side) while blocking reverse flow. This characteristic makes diodes essential in a variety of applications, including rectification processes, where alternating current (AC) is converted to direct current (DC). In contrast, a transistor is a semiconductor device used for amplification or switching but does not inherently provide one-directional current flow like a diode. An inductor, part of a circuit that stores energy in a magnetic field when current flows through it, does not govern the direction of current flow and can support alternating current in both directions. A resistor, on the other hand, is a component used to limit or regulate the flow of electric current in a circuit but also does not restrict the flow to one direction, as it is a passive component. Therefore, in the context of devices that strictly allow current to flow in one direction, diodes are the definitive choice.