An electrode is a conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, 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] In science and engineering, conductors are materials that contain movable charges of electricity. ... An electrical network or electrical circuit is an interconnection of electrical elements such as resistors, inductors, capacitors, diodes, switches and transistors. ... A semiconductor is a material with an electrical conductivity that is intermediate between that of an insulator and a conductor. ... An electrolyte is a substance which dissociates free ions when dissolved (or molten), to produce an electrically conductive medium. ... For other uses, see vacuum cleaner and Vacuum (musical group). ... Michael Faraday Michael Faraday (September 22, 1791 – August 25, 1867) was a British scientist (a physicist and chemist) who contributed significantly to the fields of electromagnetism and electrochemistry. ... Amber pendants. ... Electricity is a general term applied to phenomena involving a fundamental property of matter called an electric charge // Related concepts Lightning strikes during a night-time thunderstorm. ...

Anode and cathode in electrochemical cells

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. Diagram of a zinc anode in a Daniells cell. ... Diagram of a copper cathode in a Daniells cell. ... An electrochemical cell is a setup used for creating an electromotive force(voltage) in a conductor separating two reactions. ... An electrochemical cell is a setup used for creating an electromotive force(voltage) in a conductor separating two reactions. ... Diagram of a zinc anode in a Daniells cell. ... Diagram of a copper cathode in a Daniells cell. ... The most fundamental reactions in chemistry are the redox processes. ... Reduction or reducing has several meanings: In mathematics, reduction is the process of manipulating a series of equations or matrices into a desired simpler format. ...

Primary cell

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. It can be discharged but not recharged. A primary cell is any kind of electrolytic cell in which the electrochemical reaction of interest is not reversible. ...

Secondary cell

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, with the anode as the negative electrode and the cathode as the positive. A secondary cell is any kind of cell in which the electrochemical reaction of interest is reversible. ... Rechargeable batteries are batteries that can be restored to full charge by the application of electrical energy. ... Electrolytic cells are composed of an electrolyte (usually water or another solvent capable of dissolving various ions of interest), a cathode and an anode. ... Voltaic cell can connote: Galvanic cell Voltaic pile see also: battery (electricity), fuel cell This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ...

Other anodes and cathodes

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. In electronics, a vacuum tube (U.S. and Canadian English) or (thermionic) valve (outside North America) is a device generally used to amplify, or otherwise modify, a signal by controlling the movement of electrons in an evacuated space. ... A semiconductor is a material with an electrical conductivity that is intermediate between that of an insulator and a conductor. ... Types of diodes In electronics, a diode is a component that restricts the direction of movement of charge carriers. ... An electrolyte is a substance which dissociates free ions when dissolved (or molten), to produce an electrically conductive medium. ...

In a three-electrode cell, a counter electrode, also called an auxilliary 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. Noble metals are metals that are resistant to corrosion or oxidation, unlike most base metals. ... Graphite (named by Abraham Gottlob Werner in 1789, from the Greek γραφειν: to draw/write, for its use in pencils) is one of the allotropes of carbon. ...

Welding electrodes

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. Manual Metal Arc welding, also known as stick or MMA welding is one of the most common forms of welding. ... Gas metal arc welding (GMAW), sometimes referred to by its subtypes, metal inert gas (MIG) welding or metal active gas (MAG) welding, is a semi-automatic or automatic arc welding process in which a continuous and consumable wire electrode and a shielding gas are fed through a welding gun. ... It has been suggested that MMA welding be merged into this article or section. ... Gas tungsten arc welding Gas tungsten arc welding (GTAW), commonly known as tungsten inert gas (TIG) welding or wolfram inert gas (WIG) welding, is an arc welding process that uses a nonconsumable tungsten electrode to produce the weld. ...

Alternating current electrodes

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 periodically, usually many times per second. city lights viewed in a motion blurred exposure. ... city lights viewed in a motion blurred exposure. ... The hertz (symbol Hz) is the SI unit of frequency. ...

Types of electrode

• Electrodes for medical purposes, such as EEG, EKG, ECT, defibrillator
• Electrodes for Electrophysiology techniques in biomedical research
• Electrodes for execution by the electric chair
• Electrodes for electroplating
• Electrodes for arc welding
• Electrodes for cathodic protection

EEG can mean: Electroencephalography - the method and science of recording and interpreting traces of brain electrical activity as recorded from the skull surface or the device used to record such traces Emperor Entertainment Group - A Hong Kong entertainment company. ... ECG may also refer to the East Coast Greenway Lead II An Electrocardiogram (ECG or EKG, abbreviated from the German Elektrokardiogramm) is a graphic produced by an electrocardiograph, which records the electrical voltage in the heart in the form of a continuous strip graph. ... ect has several meanings the suffix -ect, as in correct, connect ECT electroconvulsive therapy a common misspelling of Etc. ... Bold text A semi-automatic external defibrillator (AED) A defibrillator is a medical device used in the defibrillation of the heart. ... This article needs to be cleaned up to conform to a higher standard of quality. ... The first electric chair, which was used to execute William Kemmler in 1890 The electric chair is a device used in some states in the United States for execution of criminals convicted of capital crimes, usually capital murder. ... Electroplating is the coating of an electrically conductive item with a layer of metal using electrical current. ... Manual Metal Arc welding, also known as stick or MMA welding is one of the most common forms of welding. ... Aluminium anodes mounted on a steel jacket structure Cathodic protection (CP) is a technique to control the corrosion of a metal surface by making that surface the cathode of an electrochemical cell. ...

See also

• battery
• redox
• cathodic protection
• Galvanic cell
• anion vs. cation
• electron vs. hole
• electrolyte
• electron microscope

Four double-A (AA) rechargeable batteries In science and technology, a battery is a device that stores energy and makes it available in an electrical form. ... Redox reactions include all chemical processes in which atoms have their oxidation number (oxidation state) changed. ... Aluminium anodes mounted on a steel jacket structure Cathodic protection (CP) is a technique to control the corrosion of a metal surface by making that surface the cathode of an electrochemical cell. ... The Galvanic cell, named after Luigi Galvani, consists of two metals connected by an electrolyte which forms a salt bridge between the metals. ... An anion is an ion with negative charge. ... A cation is an ion with positive charge. ... Properties The electron is a fundamental subatomic particle which carries a negative electric charge. ... In solid state physics, an electron hole (usually referred to simply as a hole) is the absence of an electron from the otherwise full valence band. ... An electrolyte is a substance which dissociates free ions when dissolved (or molten), to produce an electrically conductive medium. ... A transmission electron microscope. ...

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).