Thermistors (AQA GCSE Physics: Combined Science)

• A thermistor is a non-ohmic conductor and a temperature-dependent resistor
• It is represented by the following circuit symbol:

Thermistor circuit symbol

• The resistance of a thermistor changes depending on its temperature
  • As the temperature increases the resistance of a thermistor decreases and vice versa

The resistance through a thermistor is dependent on the temperature of it

• A thermistor is a temperature sensor and is regularly used as a thermostat
  • This means it automatically regulates temperature or activates a device when the temperature reaches a certain point

• Therefore, thermistors are found in:
  • Ovens
  • Refrigerators
  • Fire alarms
  • Digital thermometers
  • Boilers

• They are commonly used to regulate and monitor the temperature in environments where it must be carefully controlled eg. food and beverage factories

A digital thermometer uses a thermistor to display a temperature reading