What electronic component can be used as a switch or variable resistor?

The potentiometer is an electronic component that can function both as a switch and a variable resistor. This versatility stems from its design, which typically consists of a resistive element and a movable contact called a wiper. When the wiper is adjusted along the resistive track, it changes the resistance that the component presents to the circuit, allowing it to control the flow of current.

As a switch, a potentiometer can serve to open or close a circuit by selecting between different resistive paths or completely disengaging the circuit when turned to an off position. This makes it especially useful in applications such as volume controls in audio devices or adjusting brightness in lighting systems, where fine-tuning the resistance is necessary to achieve the desired effect.

The other components listed have distinct functions that do not align with both switching and variable resistance roles. Capacitors store electric charge and are not designed to regulate current like a variable resistor, while inductors store energy in a magnetic field and are used primarily in filtering and energy storage applications. Transistors, while they can act as switches, operate based on current control and amplification rather than providing variable resistance in the same direct manner as a potentiometer.