Equivalent Circuit for the Uncompensated Resistances Occurring at Ring-Disk Electrodes

An equivalent circuit for the ring-disk electrode is proposed and tested. The model assumes that the resistance between the auxiliary electrode and the disk (or ring) electrode is the series combination of two resistances. One resistance is shared by both the disk and the ring electrodes, whereas the other is characteristic of the disk (or the ring) electrode. Changing the position of the Luggin capillary tip produces different uncompensated ohmic potential drops. The IR drops can be interpreted by assuming that the tip of the Luggin capillary is being located somewhere on these resistances.