Answer to Question #169707 in Physics for Pushpo

Question

What is meant by surface tension and surface energy? Explain the molecular theory of surface tension in detail. Establish a relation between the surface tension and surface energy.  

Answer 1

Surface tension is the tendency of liquid surfaces to shrink into the minimum surface area possible. Surface tension has the dimension of force per unit length, or of energy per unit area.

Surface free energy or interfacial free energy or surface energy quantifies the disruption of intermolecular bonds that occurs when a surface is created.

Surface tension has been well- explained by the molecular theory of matter. According to this theory, cohesive forces among liquid molecules are responsible for the phenomenon of surface tension. The molecules well inside the liquid are attracted equally in all directions by the other molecules.

So, surface tension of a liquid is equal to the work done in increasing the surface area of its free surface by one unit. In other words, surface tension is equal to surface energy per unit area.

$$E_s=T\Delta A$$