Electrode Electrode An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte, a vacuum or air). The word was coined by William Whewell at the request of the scientist Michael Faraday from two Greek words: "elektron", meaning amber (from which the word electricity is derived), and "hodos", a way. The electrophore, invented by Johan Wilcke, was an early version of an electrode used to study static electricity. An electrode in an electrochemical cell is referred to as either an "anode" or a "cathode" (words that were coined by William
Plate electrode tube envelope and is cooled by radiation cooling, forced air or water. A problem in early vacuum tubes was "secondary emission"; electrons striking the plate could knock other electrons out of the metal surface. In some tubes such as tetrodes these "secondary electrons" could be absorbed by other electrods such as grids in the tube, resulting in a current out of the plate. This current could cause the plate circuit to have negative resistance, which could cause unwanted parasitic oscillations. To prevent this most plates in modern tubes are given a chemical coating which reduces secondary emission. Plate electrode A