Plot a graph of change in resistance (R) against temperature (), with resistance on the y-axis.
Conclusion The smooth curve shows that as the temperature of the thermistor increases, the resistance decreases.
Precautions ■ Make sure there is enough glycerol to cover the thermistor. ■ Use a digital thermometer as it is accurate to 0.1 C. ■ Heat the water slowly, so as to ensure the thermistor is the same temperature as the glycerol, or start at high temperature and take readings as the wire cools.
■ The more readings you take, the more accurately you can plot the graph.
■ Ensure the temperature and the resistance are taken simultaneously. Resistance vs. temperature 1000
800 600 400 200
0 20
40 Temperature / °C
60 Fig 19.17
Safety Precaution Take care when handling hot apparatus.
Note
Glycerol is used instead of water in the boiling tube because it makes a better thermal contact with the thermistor, thus ensuring that the thermometer gives an accurate reading of the temperature of the thermistor. Note
This experiment can be used as Mandatory Experiment 8: Calibration curve of a thermometer using the laboratory mercury thermometer as a standard.
