Soap film equilibrium shapes

A freshly formed surface of a soap film reaches its equilibrium shape in the order of seconds. However the thickness of the film reaches its equilibrium value in a time that is orders of magnitude greater than that for the surface. For the fastest draining films, of low surface viscosity, this will be minutes whilst films of high surface viscosity will take hours to drain to their equilibrium thickness. 

Soap films contained by a circular ring (a) a non-equilibrium soap film (b) the equilibrium soap film having the shape of a disc. 

Another interesting example is obtained with a wire boundary in the shape of a pair of earphones (Fig. 4.4). There are three possible equilibrium configurations for the soap film (Figs. 4.4(a), (b), and (c)). Figures (a) and (b) have... 

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