NON-OHMIC RESISTANCE (BEHAVIOR)

"A system or system element is behaving ""non-ohmically"" if it does not follow Ohm's law. That is, the value of the resistance depends on the current or the potential. Opposite: ohmic behavior. The resistance can be formally defined as the differential of the potential with respect of the current. In the case of Ohm's law, this is the constant value of the resistance. In electrochemistry, a typical ""non-ohmic"" element is the charge-transfer resistance. The charge-transfer reaction can be considered a circuit element because it requires a certain amount of overpotential to force through a current. However, the pertinent relation here is the Tafel law (at least at relatively large overpotentials), and the differential of the current (that is the resistance) is a function of the current itself. "