The word thermistor is a compound word derived from “thermo” (meaning heat) and resistor. It is actually a combination of heat and resistor, as its resistance vary directly or inversely to the temperature.

So, there are basically two types of thermistors, which are:

  1. NTC and
  2. PTC
  1. NTC means Negative Temperature Co-efficient, and its resistance varies inversely proportional to the applied temperature.
  2. PTC on the other Hand is Positive Temperature Co-efficient as its resistance varies directly proportional to the applied temperature.

Thermistors when connected in series with a resistor gives a corresponding change in voltage whenever the temperature is changed. This could be used to monitor the temperature of the thermistor surrounding by merely measuring the voltage across the thermistor.

Thermistor in series with Resistor

Check how Thermistors look like.