In general, how many terminals does a variable resistor usually have?

• A. Two
• B. Three
• C. Four
• D. Five

Answer: (B)

A variable resistor is typically a potentiometer, which has three terminals: the two ends of the resistive track and a movable contact (the wiper) that taps the track. The wiper lets you pick any point along the resistance, so the resistance between the wiper and either end varies as you turn the knob or slide the control. The overall resistance between the two ends stays fixed, making it ideal as a voltage divider or adjustable signal source. In some cases you might only use two terminals (end and wiper) to function as a rheostat, but three terminals is the standard for a general variable resistor. Four or five terminals would imply additional taps or shielding not needed for a typical variable resistor.