A simple optical experiment to determine the gas constant

Abstract

An undergraduate experiment employing optical technique to determine the gas constant has been developed. The principle of the measurements is based on the strong correlation between the refractive index and the density of the gas. An interferometer is used to measure the change in the refractive index (hence change in density) of the gas as the pressure is varied. The value of the gas constant is obtained by comparing the results to the ideal gas equation (we assume that in our experiment the gas can be considered as ideal). The operation of the setup is simple and the accuracy is sufficient. We believe that the experiment can offer excellent training to students not only on the experimental aspect but also on the subject matter involved.