Determination of absolute zero temperature from thermistor voltage noise

We present a simple experiment to determine absolute zero temperature by measuring the Johnson noise of a thermistor. Using the thermistor itself as a temperature sensor, we measure the thermistor voltage noise at different temperatures by submerging the thermistor in hot and cold water contained in a thermally insulated cup. A linear fit of the data yields an absolute zero temperature of -274 ± 14 °C, agreeing with the accepted value. The experiment is simple enough to be performed at most universities as a part of an undergraduate experimental physics course.