Monday, 9 February 2015

An Electrode


An electrode is an electron conductor together with a counter electrode with a medium located between two electrodes interacts. Electrodes are serene of electrical conductors, frequently a metal or graphite. They are used to connect non-electron-conducting regions with cables and find this example application in electrochemical cells, as a tool (eg. As in resistance spot welding) and possibly material dispenser during arc welding, as terminals and electro-optical elements in electron tubes. About the electrical function beyond electrode material may be deposited or consumed, or there may be physical processes taking place in the electrode as the anode of an X-ray tube.

 Electrodes in the gas or vacuum or insulator
 Depending on the type of the medium surrounding the electrode leads to different forms of interaction:

 If the medium is an insulator, an electric field is established between the electrodes. This pattern is called condenser. however, silent electric discharge.

 If the medium is a vacuum or a gas, so an electric field between the electrodes is built up as in the case of the insulator. However, electrons from one electrode (cathode) move to another when the exit from the cathode is made possible, eg. As by field emission or thermal emission or the Thermionic emission (→ electron tube, x-ray tube, thermionic cathode).

 If the medium is a gas, the atoms or molecules of the gas are partially ionized, so that a plasma is formed. In plasma, the ions move next to the electrons in the electric field (→ gas discharge lamp).

 Also, the spark plug electrodes, welding electrodes in arc welding and the electrodes inside the nozzle for plasma cutting fall into this category. The welding electrodes generate an arc welding with the material to be welded. In the heat of the arc both melt and the electrode is used as filler material, so that the materials are joined.