Electrical resistivity and conductivity ions. In biological membranes, currents are carried by ionic salts. Small holes in cell membranes, called ion channels, are selective to specific ions and determine the membrane resistance. The electrical resistivity of a metallic conductor decreases gradually as temperature is lowered. In ordinary conductors, such as copper or silver, this decrease is limited by impurities and other defects. Even near absolute zero, a real sample of a normal conductor shows some resistance. In a superconductor, the resistance drops abruptly to zero when the material is cooled below its critical temperature. An electric current flowing in a loop of superconducting wire
Electrical conductivity meter develop a model to calculate concentration of the liquid. Concentration of pure liquids can be calculated when the conductivity and temperature is measured. The preset curves for various acids and bases are commercially available. For example, it is possible to measure the concentration of high purity hydrofluoric acid using conductivity based concentration measurement [Zhejiang Quhua Fluorchemical, China Valmet Concentration 3300]. Benefit of conductivity and temperature based concentration measurement is the superior speed of inline measurement compared to on-line analyzer. Conductivity based concentration measurement has limitations. The concentration-conductivity dependence of most acids and bases is not linear. Conductivity based measurement can’t