Potentiometer

A variable resistor with a sliding wiper, used to adjust voltage or resistance manually.

How it works

A potentiometer (often called a "pot") is a three-terminal variable resistor. It contains a resistive track and a conductive wiper that slides along the track when you turn the knob. The resistance between the two outer terminals is fixed, but the resistance between the middle wiper and the outer terminals changes as the wiper moves.

When all three terminals are used, it acts as a variable voltage divider, perfect for volume controls or setting reference voltages. If you only connect the wiper and one outer terminal, it acts as a simple variable resistor (rheostat) to control current.

Key Formulas

Voltage Divider OutputV_out = V_in × (R_bottom / (R_top + R_bottom))

Common Mistakes

Using a potentiometer to directly control the current of a heavy load (like a motor or high-power LED). The wiper contact is delicate and will burn out if subjected to more than a few milliamps.

Common Variants

10kΩ Pot (Linear)

The standard value for feeding a variable analog voltage into a microcontroller input, chosen specifically to balance low current draw against low susceptibility to noise pickup.

100kΩ Pot (Log/Audio)

A higher-resistance, logarithmic-taper potentiometer built specifically for audio volume control, where the non-proportional resistance curve is chosen to match how loudness is perceived, not to measure position.