How does conductivity measurement work?

Conductivity measures a solution's ability to conduct electrical current, which depends on ion concentration, ion mobility, and temperature. A conductivity sensor applies AC voltage between electrodes and measures resulting current. Results are expressed in Siemens per meter (S/m) or microSiemens per centimeter (uS/cm). Pure water has very low conductivity (~0.05 uS/cm); seawater has high conductivity (~50,000 uS/cm). Conductivity indicates total dissolved solids and is used for water quality and chemical concentration monitoring.