GCSE Physics (AQA)

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Thermistors

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Electricity Current, potential difference and resistance

Thermistors

3:40 Resistance of Circuit Components
Spec 4.2.1.1 4.2.1.4
Previous Diodes Next Light-Dependent Resistors
  • Thermistor resistance decreases as temperature increases.
  • Most components increase resistance with temperature, but thermistors decrease.
  • Thermistors contain special material that releases more charge carriers with temperature changes.
  • GCSE students need to know the circuit symbol for a thermistor, resembling a resistor with a line through it.
  • Thermistor properties can be tested by suspending it in a heated water bath.
  • The experiment setup includes a thermistor in a water bath, measuring temperature as the independent variable.
  • A circuit with a cell, ammeter, and voltmeter measures current and potential difference.
  • Resistance is calculated using R = V/I, with resistance as the dependent variable.
  • Results are plotted on a graph with temperature on the horizontal axis and resistance on the vertical axis, showing a smooth curve.
  • Low temperature results in high resistance; high temperature results in low resistance.
  • Some thermostats increase resistance with temperature, but not required knowledge for GCSE.
  • Thermistors are used in devices needing to react to temperature changes, like fire alarms and fridges.
  • Fire alarms use thermistors to restrict current until high temperature triggers an alarm.
  • Fridges use thermistors to adjust cooling power based on internal temperature.
  • GCSE exams may require explaining thermistor use in devices, not recalling specific examples.

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