Potential analysis method used in the electrode is called a galvanic cell. Primary battery is a system, its role is to make the chemical energy into electricity. The battery voltage is called the electromotive force (EMF). The electromotive force (EMF) consists of two half cell. One and a half cells called measuring electrode, and its potential is associated with specific ion activity; Another one and a half in reference battery, often referred to as the reference electrode, it is general and measuring solution are interlinked, and connected to the measuring instrument.

    For example, an electrode formed a thong in the salt solution of silver ions in a silver conductor is made, at the interface between conductor and solution, because the metal salt solution and two phase different activity of silver ion, it forms ions of charging process, and form a certain potential difference. Lose electronic silver ions into the solution. When there is no reverse charge the current stage, that is not current, a process that will eventually reach a balance. In this state of equilibrium voltage is called the half cell potential or existing in the electrode potential.

    This (as above) is composed of metal and solution containing this metal ion electrode is called the first kind of electrode.

    The measurement of this potential is relatively a potential has nothing to do with the composition of the salt solution of reference electrode. The reference electrode with independent potential is also known as the second electrode. For such electrodes, metal wires are covered a layer of the metal micro soluble salt (such as: Ag/AgCl), and inserts in electrolyte solution containing this kind of metal salt anions. The half cell potential or the size of the electrode potential depends on the activity of the anion.

The voltage between two electrodes follow the NERNST (NERNST formula: