Falling temperatures: A simple estimation of the absolute zero

When teaching an introductory course on thermal physics, one of the important challenges that a college physics teacher faces is to introduce to his/her students to the idea of an absolute minimum for the temperature, the so called ‘absolute zero. Indeed, given that the experiments used to determine the absolute zero temperatura are usually performed in advanced thermodynamics courses, the usual procedure in introductory levels consists of passing on the notion based on the authority of a textbook. The aim of this article is to present a straightforward and low-cost experiment that allows introducing the notion of an absolute minimum temperature. The values obtained for the minimum temperature are in excellent agreement with the actual value of -273.15°C.