Electrode electrode. In a vacuum tube or a semiconductor having polarity (diodes, electrolytic capacitors) the anode is the positive (+) electrode and the cathode the negative (−). The electrons enter the device through the cathode and exit the device through the anode. Many devices have other electrodes to control operation, e.g., base, gate, control grid. In a three-electrode cell, a counter electrode, also called an auxiliary electrode, is used only to make a connection to the electrolyte so that a current can be applied to the working electrode. The counter electrode is usually made of an inert material, such as a
Silver chloride electrode bond with silver of the electrode resulting in silver chloride and free electrons to deliver to the lead wire. The reaction allows current to pass from electrolyte to electrode and the electron current passes through the lead wire for the instrument to read. When there is an uneven distribution of cations and anions, there will be a small voltage called "half-cell potential" associated with the current. In the DC system that is used by the ECG and EEG instruments, the difference between the half-cell potential and the zero potential is shown as DC offset which is an undesirable characteristic. Silver/silver