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| − | An '''electrode''' is a conductor used to make contact with a nonmetallic part of a circuit (e.g. a [[ |
+ | An '''electrode''' is a conductor used to make contact with a nonmetallic part of a circuit (e.g. a [[skin]], an [[electrolyte]] or a vacuum). The word was coined by the scientist Michael Faraday from the Greek words ''elektron'' (meaning amber, whence the word [[electricity]] is derived) and ''hodos'', a way.<ref>Michael Faraday, "[http://dbhs.wvusd.k12.ca.us/Chem-History/Faraday-electrochem.html On Electrical Decomposition]", ''Philosophical Transactions of the Royal Society'', [[1834]] (in which Faraday coins the words ''[[electrode]]'', ''[[anode]]'', ''[[cathode]]'', ''[[anion]]'', ''[[cation]]'', ''[[electrolyte]]'', ''[[electrolyze]]'').</ref> |
| + | They are used in [[electrophysiology]] studies. |
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| − | == Anode and cathode in electrochemical cells == |
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| − | An electrode in an [[electrochemical cell]] is referred to as either an ''[[anode]]'' or a ''[[cathode]]'', words that were also coined by Faraday. The anode is defined as the electrode at which electrons come up from the cell and [[oxidation]] occurs, and the cathode is defined as the electrode at which electrons enter the cell and [[reduction]] occurs. Each electrode may become either the anode or the cathode depending on the voltage applied to the cell. A bipolar electrode is an electrode that functions as the anode of one cell and the cathode of another cell. |
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| − | === Primary cell === |
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| − | A [[primary cell]] is a special type of electrochemical cell in which the reaction cannot be reversed, and the identities of the anode and cathode are therefore fixed. The anode is always the negative electrode. The cell can be discharged but not recharged. |
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| − | == |
+ | ==See also== |
| + | [[Stimulators (apparatus)]] |
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| − | A [[secondary cell]], for example a [[rechargeable battery]], is one in which the reaction is reversible. When the cell is being charged, the anode becomes the positive (+) electrode and the cathode the negative (−). This is also the case in an [[electrolytic cell]]. When the cell is being discharged, it behaves like a primary or [[voltaic cell|voltaic]] cell, with the anode as the negative electrode and the cathode as the positive. |
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| − | == Other anodes and cathodes == |
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| − | In a [[vacuum tube]] or a [[semiconductor]] having polarity ([[diode]]s, [[electrolytic|electrolytic capacitor]]s) 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. |
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| − | 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 [[noble metal]] or [[graphite]], to keep it from dissolving. |
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| − | == Welding electrodes == |
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| − | In [[arc welding]] an electrode is used to conduct current through a workpiece to fuse two pieces together. Depending upon the process, the electrode is either consumable, in the case of [[gas metal arc welding]] or [[shielded metal arc welding]], or non-consumable, such as in [[gas tungsten arc welding]]. For a direct current system the weld rod or stick may be a cathode for a filling type weld or an anode for other welding processes. For an alternating current arc welder the welding electrode would not be considered an anode or cathode. |
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| − | == Alternating current electrodes == |
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| − | For electrical systems which use [[alternating current]] the electrodes are the connections from the circuitry to the object to be acted upon by the electrical current but are not designated anode or cathode since the direction of flow of the electrons changes [[alternating current|periodically]], usually [[hertz|many times per second]]. |
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| − | == Types of electrode == |
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| − | *Electrodes for medical purposes, such as [[Electroencephalography|EEG]], [[EKG]], [[ECT]], [[defibrillator]] |
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| − | *Electrodes for [[Electrophysiology]] techniques in biomedical research |
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| − | *Electrodes for execution by the [[electric chair]] |
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| − | *Electrodes for [[electroplating]] |
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| − | *Electrodes for [[arc welding]] |
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| − | *Electrodes for [[cathodic protection]] |
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| − | *Inert electrodes for [[hydrolysis]] (made of [[platinum]]) |
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| − | == See also == |
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| − | *[[Battery (electricity)|battery]] |
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| − | *[[redox]] |
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| − | *[[cathodic protection]] |
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| − | *[[Galvanic cell]] |
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| − | *[[anion]] vs. [[cation]] |
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| − | *[[electron]] vs. [[electron hole|hole]] |
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| − | *[[electrolyte]] |
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| − | *[[electron microscope]] |
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== References == |
== References == |
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== External links == |
== External links == |
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| + | [[Category:Apparatus]] |
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| − | *[http://www.valence.com/BatteryEducation.asp Valence Technologies Inc. battery education page] |
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[[Category:Electrophysiology]] |
[[Category:Electrophysiology]] |
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[[Category:Electrode]] |
[[Category:Electrode]] |
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| − | [[cs:Elektroda]] |
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| − | [[de:Elektrode]] |
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| − | [[es:Electrodo]] |
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| − | [[fr:Électrode]] |
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| − | [[io:Elektrodo]] |
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| − | [[id:Elektroda]] |
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| − | [[it:Elettrodo]] |
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| − | [[he:אלקטרודה]] |
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| − | [[nl:Elektrode]] |
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| − | [[ja:電極]] |
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| − | [[no:Elektrode]] |
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| − | [[pl:Elektroda]] |
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| − | [[pt:Eletrodo]] |
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| − | [[sv:Elektrod]] |
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| − | [[zh:电极]] |
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{{enWP|Electrodes}} |
{{enWP|Electrodes}} |
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An electrode is a conductor used to make contact with a nonmetallic part of a circuit (e.g. a skin, an electrolyte or a vacuum). The word was coined by the scientist Michael Faraday from the Greek words elektron (meaning amber, whence the word electricity is derived) and hodos, a way.[1]
They are used in electrophysiology studies.
See also
References
- ↑ Michael Faraday, "On Electrical Decomposition", Philosophical Transactions of the Royal Society, 1834 (in which Faraday coins the words electrode, anode, cathode, anion, cation, electrolyte, electrolyze).
External links
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