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Code Number: 5D20.50
Demo Title: Thermistors - Differential Negative Resistance
Condition: Excellent
Principle: Electrical Resistance vs. Temperature
Area of Study: Electricity & Magnetism
Equipment:
Multimeter, Thermistors with Attached Banana Plugs, Hot and Cold Baths.
Procedure:
Prepare a hot and cold bath of the desired temperature. Hot water out of the tap will work but boiling water would be better. Ice water will work but a dry ice/alcohol bath would be better. Liquid nitrogen is probably too cold an will break the thermistor. When you have your hot and cold bath, dip in the thermistor and monitor the resistance. Unlike copper wire and most resistors, the thermistor resistance will go up as it gets cold and go down as it gets hot.
References:
- Edward Roob III, Robert F. Bouscher, Ethan I. Kleinbaum, David Sederberg, and Gabor Csathy, "Too Cool Two - Service Learning and Faculty Engagement in Physics Outreach", TPT, Vol. 58, #1, Jan. 2020, p. 28.
- Kyle Forinash and Raymond F. Wisman, "Smartphones—Experiments with an External Thermistor Circuit", TPT, Vol. 50, #9, Dec. 2012, p. 566.
- Karl Jakus, "Physics Experiment #4: Temperature Measuring Instrumentation: Thermistors", Keithley Instruments, Series II.
- Forrest M. Mims III, "Thermistor Circuits", Science and Communication Circuits & Projects, p. 36 & 37.