Reference electrode: Definition
A reference electrode is used in measuring the working electrode potential of an electrochemical cell. A reference electrode should have a stable electrochemical potential as long as no current flows through it. The most common laboratory reference electrodes are the Saturated Calomel Electrode (SCE) and the Silver/Silver Chloride (Ag/AgCl) electrodes. In field probes, a (a piece of the working electrode material) can be used. A Luggin capillary is often used to position the sensing point of a reference electrode to a desired point in a cell.