Conductivity

Conductivity is defined as the ability of a substance to conduct an electrical current and is inversely proportional to resistance. The unit commonly used to measure conductivity is Siemens per centimetre (S/cm). To give you some idea how this relates, the conductivity of pure water is 0.055 µS/cm, compared with 52 mS/cm of sea water. In aqueous solutions, conductivity is directly proprtional to the concentration of total dissolved solids (TDS) as salts. The higher the concentration of solids, therefore, the greater the conductivity. 

Conductivity is a variable that is monitored in many fields, from the chemical industry and agriculture to breweries, even the graphic arts industry.