What is a Thermistor

Thermistor:

A thermistor is a semi-conducting material such as mixtures of oxides of copper, manganese, cobalt, etc.  in the form of a fused bead connected to two leads. As its temperature is increased its resistance rap-
idly decreases.
Typical resistance/temperature curves
for a thermistor and common metals are shown in figure below.
The resistance of a typical thermistor can
vary from 400 W at 0°C to 100 W at 140°C.

Advantages of thermistor:

The main advantages of a thermistor are its high sen-
sitivity and small size. It provides an inexpensive
method of measuring and detecting small changes in
temperature.