What is Surface Tension?

Surface tension is a quantity which we often deal with in daily life without realizing it. It plays a role in washing and cleaning procedures as well as in lubricants as used in automobiles and cosmetics. The only reason the Water Beetle does not drown is because it is being held up by surface tension.
Surface tension is created through the attraction of the molecules in liquids to each other. If one views a molecule at the interior of a medium, it would be equally attracted by all neighboring molecules. The effect is that it is attracted to all sides with the same force, so that the resulting force is zero (see picture).
On the other hand, if a molecule is located at the surface of a liquid, the attraction from the interior of the medium works further on the one side, whereas there are no more molecules from the other side. Hence the resulting force is directed towards the interior of the liquid. On the microscopic scale this causes drops of liquid to be round since the surface of the liquid is being minimized that way. Therefore, surface tension is defined as the energy needed to increase the surface by a defined value. Therefore, the minimum surface corresponds to the minimum energy.

	Surface Tension - Measuring Methods
	Surface Tension Experiments
	Surface Tension - Special Values

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