Fri October 21, 2011 By: Nafila Kp

what is the relation between surface energy and surface tension?

Expert Reply
Sat October 22, 2011

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
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