The so-called potentiometer exponential, logarithmic, linear relation, is refers to the resistance value of the potentiometer with sliding contact point rotation angle division, this relation in theory can be any function of the form, but the only these three types, as shown in figure A, B, C indicates the situation. When in use, the linear potentiometer, the resistance changes with the angle of a linear relation, which is suitable for the voltage divider.

Exponential (reverse logarithmic) potentiometer, at the start of rotation, the resistance changes a lot. While in the corner is close to the maximum resistance is smaller, the resistance variation. Tone control circuit of the potentiometer is suitable for audio circuit is exponential (C).

Logarithmic potentiometer at the start of rotation, the resistance value change little, while in the corner is close to the maximum resistance is greater, the resistance variation.

Because the human ear is sense of volume approximately a linear relationship between the logarithm of sound power and sound, that small increase, the human ear is sensitive, but to a certain value, even if the sound power has been greatly increased, the ear feels little change. The resistance variation of visible logarithmic potentiometer is in line with the characteristics of human auditory, therefore in the radio, television and other volume control circuit, should choose a logarithmic potentiometer.