Learn the basics of Electrical Engineering.

Basics of Thermsitor [NTC Thermistor vs PTC Thermistor]

What is thermistor

A thermistor is a two terminal component whose resistance changes with the change in temperature. It is also known as a thermal resistor. A thermistor is actually a two terminal transducer whose electrical resistance varies based on the external physical conditions. The name thermistor itself is a combination of thermal and resistors.



NTC or negative temperature coefficient thermistor is the one whose resistance decreases with the increases in temperature. They are used as temperature sensor. The figure below displays the resistance vs temperature curve and physical look of NTC.
NTC's are usually made from semiconductors whose charge carriers and thus the conduction increases with the increase in temperature.

Practical applications

  • Used as a resistance thermometer for measuring temperature
  • As engine coolant monitor in vehicles
  • To monitor the temperature of battery banks
  • To monitor the heating in 3D printers


The resistance of PTC or positive temperature coefficient resistors increases with the increases in temperature. 
PTC's are made from polycrystalline compounds which are doped in a manner that causes their resistance to increases with the increase of temperature.

Practical applications

  • Used in wax motors to provide the heat
  • Is installed in motor windings for protection
  • Is used as current limiting devices for monitoring the temperature

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