what is the relation between surface energy and surface tension?
Relation between surface tension and surface energy
consider a liquid film to be formed on a rectangular surface ABCD. On forming a film, the surface film contracts (see arrows) due to surface tension i.e., AB is pulled inwards. To keep AB in its original position, a force F is applied in the outward direction, all along its length. If T is force due to surface tension (i.e. T=F/l).
Then F = T x 2l. Since the film has two free surfaces, the RHS of the equation is multiplied by 2.If the wire AB is to be pulled by an additional distance dx, then the additional work done W in this case is,
i.e. Work done in increasing the surface area by unity, is equal to the surface tension T at constant temperature. Therefore, this work done, is the surface energy of the film