A potentiometer is a variable resistor. A resistor is an electric component that resists the flow of electricity, slowing it down, but not stopping it.Unlike with a normal resistor, the resistance of a potentiometer can be changed, usually either by turning a knob or adjusting a slider. terminal called the base in the potentiometer attaches to a strip of a resistive element, such as graphite. Another terminal called the wiper attaches to a blade that rubs against the resistor. When the slider is moved or the knob is turned, the wiper moves along the resistor strip.