Surface tension effects of surface tension can be seen with ordinary water: Surface tension is visible in other common phenomena, especially when surfactants are used to decrease it: Surface tension, represented by the symbol "γ" (alternatively "σ" or "T"), is measured in force per unit length. Its SI unit is newton per meter but the cgs unit of dyne per centimeter is also used. For example, Surface tension can be defined in terms of force or energy. In terms of force: surface tension of a liquid is the force per unit length. In the illustration on the right, the rectangular frame, composed
Surface tension interfaces, one inside and one outside. Surface tension is dependent on temperature. For that reason, when a value is given for the surface tension of an interface, temperature must be explicitly stated. The general trend is that surface tension decreases with the increase of temperature, reaching a value of 0 at the critical temperature. For further details see Eötvös rule. There are only empirical equations to relate surface tension and temperature: Here is the molar volume of a substance, is the critical temperature and is a constant valid for almost all substances. A typical value is = . For water