If a drop of water falls on an oily surface, the water collects and becomes a ball. However, if the drop of water falls on a clean surface, it is dispersed as a thin layer. This is because the number of molecules in the water is less than the number of molecules of fat on the surface. The oil raises the surface energy and exerts a force against the drop of water. There is essentially an electrical attraction between molecules. In this case, the force acting on the surface is called surface tension.

The surface tension increases as the density of the liquids increases. For example, when some salt is added to the water, the salt is dispersed in the water and increases the density of the water. In this case, the force between the water molecules increases and the surface tension of the water increases. Detergents and soaps reduce surface tension. Similarly, surface tension decreases with increasing temperature. Therefore, the desired cleaning is achieved when the temperature and detergents are combined.

Facial tension is an important issue in material science. The surface tension may vary depending on the temperature and the properties of the chemicals contacted with the liquid. An electrically charged surface and the surrounding solution move against each other and cause electrokinetic events. If the electrically charged particles are suspended in the liquid and electric current is applied to the system, the particles begin to move in the still liquid. This is called electrophoresis. If the velocity of the particles is measured, information is obtained about how much electricity is charged or the surface potential of that particle.

 

Surface tension tests are also performed by authorized laboratories within the scope of electrical tests. In surface tension tests, copper wires are wrapped around three samples to be measured 15 centimeters and conditioned in the furnace. Then, using copper conductors, tension is applied to the sample and the surface resistance is measured after one minute. Laboratories comply with the standards published by national and international organizations.