Surface tension

Surface tension is a physical property of liquids that manifests itself on their surface. It arises due to the attractive forces between the molecules of the liquid. Molecules inside a liquid are surrounded by other molecules and are attracted to them in all directions. On the surface of a liquid, however, there are fewer neighboring molecules, which means that the molecules on the surface are more strongly attracted to the molecules below.

These different forces of attraction create a kind of elastic layer on the surface, which is known as surface tension. The unit of surface tension is Newton per meter (N/m). The stronger the surface tension, the more resistance the surface of a liquid offers to external influences such as stretching or tearing.

Surface tension plays an important role in various physical phenomena. For example, it explains why water droplets on a surface are spherical - the surface tension tries to minimize the surface area, and the spherical shape leads to a minimal surface area. Surface tension also influences the wetting behavior of liquids on solid surfaces. Substances with low surface tension, such as greases, tend to form bead-like droplets on surfaces, while liquids with high surface tension tend to spread more evenly.

In technical applications, knowledge and control of surface tension is important, for example in the production of coatings, inks or cleaning agents. Surface tension also plays a decisive role in biological processes, such as the rise of liquids in plants through capillary action.