Goniometer/Tensiometer
Surface scientists sometimes use a Goniometer/Tensiometer to measure the surface tension and interfacial tension of a liquid using the pendant or sessile drop methods. It is a more difficult experimental measurement to accomplish and is not nearly as accurate as the Wilhelmy plate method described below. A drop is produced and the profile is then captured using a goniometer/tensiometer. The software then analyses the profile of the drop and makes a series of calculations. With pendant drops, in older, more obsolete software, the maximum diameter and the ratio between this parameter and the diameter at the distance of the maximum diameter from the drop apex is evaluated and formulas are used to derive on the basis of the Young-Laplace equation surface tension. In more current, more accurate software, the LaPlace equation itself is used to calculate surface tension for hundreds of pairs of data points along the profile of the drop. Sophisticated software routines automate this computationally intensive process.
Read more about this topic: Tensiometer (surface Tension), Types