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Definition: variable resistor

An electronic component that is used to vary the amount of current that flows through a circuit. It works by sliding a wiper terminal across a resistive material, typically a thin film or chunk of carbon or a resistive wire made of nickel chromium or tungsten alloys. After being set to the appropriate location, the wiper's position often remains fixed on the circuit board; however, it can also be made user adjustable with a screwdriver.

Pots and Rheostats
Potentiometers and rheostats are variable resistors in which the wiper terminals take the form of a dial or slider that the user does manipulate, such as the volume control of a radio or music system. A rheostat is similar to a potentiometer, but handles more power. See resistor.

Variable Resistor
As the wiper is moved across the body of the device, the resistance increases between the wiper terminal and one end terminal and decreases between the wiper and the other end. (Image courtesy of Alltronics, www.alltronics.com)

A Potentiometer
Potentiometers are variable resistors commonly used to control the volume on a radio or music system. In this example, the dial controls the wiper in the device.