AQA GCSE Physics

Revision Notes

2.1.7 Thermistors

Thermistors

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

thermistor-symbol, IGCSE & GCSE Physics revision notes

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

Thermistor, IGCSE & GCSE Physics revision notes

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

Applications of Thermistors

  • 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

Digital Thermometer, downloadable IGCSE & GCSE Physics revision notes

A digital thermometer uses a thermistor to display a temperature reading

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