Electrode lead ion in the solution being measured movements of the electric field is produced by direct contact with the solution of two electrodes. This for measuring electrode must be made of chemical resistance of the materials. Is often used in the actual materials such as titanium. Composed of two electrodes measuring electrodes called Lao shi (Kohlrausch) electrode.
Electrical conductivity measurement need to find out from two aspects. One is the solution conductivity, and the other one is in the solution 1 / A geometric relations, conductivity can be obtained by measuring current and voltage. The measuring principle in today's show directly applied in measuring instrument.
A calculated geometry size. When two area of 1 cm2 square plate, an interval of 1 cm between electrodes, the electrode constant electric and electric field under the condition of uniform, can electrode constant K = 1 cm - 1. If using this electrode measured conductance value G = 1000 mu S, the conductivity of the test solution K = 1000 mu S/cm.
In general, the electrode often form part of the non-uniform electric field. At this point, the electrode constant must be determined using standard solution. Standard solution are generally this is because the KCl conductivity using KCl solution under different temperature and the concentration of very stable, accurate. 0.1 mol/l KCl solution at 25 ℃ when the conductivity of 12.88 mS/CM.
The so-called non-uniform electric field (also called stray field, the leakage field) is not constant, but is associated with the type and concentration of ions. Therefore, a pure stray field electrode is the worst of the electrode, it through a calibration cannot satisfy the requirement of wide measurement range. `