Classification of Variable Resistor:
There are different varieties of variable resistors and they may be classified such as
1. Potentiometers or simply pots,
2. Trimmers or Presets, and
The resistance value of variable resistors, as name recommend, may be varied over the specified resistance range.
A non-linear resistor is the one, the current through which does not vary according to Ohm's law. It varies as some of function of voltage in case of Voltage Dependent Resistors (also called as varistors) or the body temperature in case of thermistors, VDRs are fundamentally non-linear resistors with negative coefficient. There are thermistors with negative temperature coefficient as well as thermistors with positive temperature coefficient.