Final answer:
A variable resistor typically has three terminals: two are connected to the resistive element and the third is the adjustable wiper that controls the resistance value.
Step-by-step explanation:
A variable resistor, often referred to as a potentiometer or rheostat depending on its particular functionality, typically has three terminals. One terminal is connected to one end of the resistive element, the second terminal is connected to the other end of the resistive element, and the third terminal, known as the wiper, slides along the resistive element. This wiper terminal allows for the adjustment of the resistance between it and either of the other two terminals.
By moving the wiper, the resistance can be varied from nearly zero (when the wiper is at the end connected to the first terminal) to its max value (when the wiper is at the end connected to the second terminal). In a circuit, a variable resistor can be used to control the voltage or current characteristics within that circuit, such as adjusting the volume on a radio or the brightness of a light.