Electrical Conductivity (EC), Electrical Resistivity, Salinity and TDS relate to the ability of a ionic solution to pass an electric current. In solutions the current is carried by cations and anions whereas in metals it is carried by electrons. How well a solution conducts electricity depends on a number of factors • Concentration • Mobility of ions • Valence of ions • Temperature In aqueous solutions the level of ionic strength varies from the low conductivity of ultra pure water to the high conductivity of concentrated chemical samples. The prob of the multimeter would be diped in the measuring sample and the parameters of the solution is calculated by applying an alternating electrical current (I) to two/four electrodes immersed in the solution and measuring the resulting voltage (V). During this process, the cations migrate to the negative electrode, the anions to the positive electrode and the solution acts as an electrical conductor.