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For other uses, see Electrode (disambiguation).

An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e. In Science and engineering, a conductor is a material which contains movable Electric charges. An electronic circuit is a closed path formed by the interconnection of Electronic components through which an Electric current can flow g. a semiconductor, an electrolyte or a vacuum). A semiconductor' is a Solid material that has Electrical conductivity in between a conductor and an insulator; it can vary over that An electrolyte is any substance containing free Ions that behaves as an electrically conductive medium This vacuum means "absence of matter" or "an empty area or space" for the cleaning appliance see Vacuum cleaner. The word was coined by the scientist Michael Faraday from the Greek words elektron (meaning amber, from which the word electricity is derived) and hodos, a way. Michael Faraday, FRS ( September 22 1791 – August 25 1867) was an English Greek (el ελληνική γλώσσα or simply el ελληνικά — "Hellenic" is an Indo-European language, spoken today by 15-22 million people mainly Amber is Fossil tree Resin, which is appreciated for its color and beauty [1]

Contents

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. An electrochemical cell is a device used for generating an Electromotive force ( Voltage) and current from chemical reactions. An anode is an Electrode through which Electric current flows into a polarized electrical device A cathode is an Electrode through which (positive Electric current flows out of a polarized electrical device The anode is now defined as the electrode at which electrons leave the cell and oxidation occurs, and the cathode as the electrode at which electrons enter the cell and reduction occurs. Redox (shorthand for reduction-oxidation reaction describes all Chemical reactions in which atoms have their Oxidation number ( Oxidation state Redox (shorthand for reduction-oxidation reaction describes all Chemical reactions in which atoms have their Oxidation number ( Oxidation state 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.

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. A primary cell is any kind of Electrochemical cell in which the electrochemical reaction of interest is not reversible so used in Disposable The anode is always the negative electrode. The cell can be discharged but not recharged.

Secondary cell

A secondary cell, for example a rechargeable battery, is one in which the reaction is reversible. See also Rechargeable electricity storage system A rechargeable battery, also known as a storage battery, is a group of two or more secondary See also Rechargeable electricity storage system A rechargeable battery, also known as a storage battery, is a group of two or more secondary 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. An electrolytic cell decomposes chemical compounds by means of electrical energy in a process called Electrolysis; the Greek word Lysis means to break up 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. The chemical change, which converts chemical energy into electrical energy, is reversible. This cell can be recharged by simply passing electrons in the opposite direction, so it is also called a storage or accumulator cell.

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 (−). This article is about the electronic device not an evacuated pipe used for experiments in Free-fall. A semiconductor' is a Solid material that has Electrical conductivity in between a conductor and an insulator; it can vary over that Dioden2jpg|thumb|right|150px|Figure 2 Various semiconductor diodes An electrolyte is any substance containing free Ions that behaves as an electrically conductive medium The electrons enter the device through the cathode and exit the device through the anode.

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. Greg Landau says The Auxiliary electrode, often also called the counter electrode, is an Electrode used in an electrochemical cell with a 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 They tend to be Precious metals often The Mineral graphite, as with Diamond and Fullerene, 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. Arc welding uses a Welding power supply to create an Electric arc between an electrode and the base material to melt the metals at the welding point 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. 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 Shielded metal arc welding (SMAW, also known as manual metal arc (MMA welding or informally as stick welding, is a manual Arc welding process that uses Gas tungsten arc welding ( GTAW) also known as tungsten inert gas (TIG welding, is an Arc welding process that uses a nonconsumable Tungsten 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.

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. An alternating current ( AC) is an Electric current whose direction reverses cyclically as opposed to Direct current, whose direction remains constant An alternating current ( AC) is an Electric current whose direction reverses cyclically as opposed to Direct current, whose direction remains constant The hertz (symbol Hz) is a measure of Frequency, informally defined as the number of events occurring per Second.

Uses of electrodes

Electric currents are run through nonmetal objects to alter them in numerous ways and to measure conductivity for numerous purposes. Examples include:

See also

References

  1. ^ 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). An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J An electron hole is the conceptual and mathematical Opposite of an Electron, useful in the study of Physics and Chemistry. An electrolyte is any substance containing free Ions that behaves as an electrically conductive medium An electron microscope is a type of Microscope that uses Electrons to illuminate a specimen and create an enlarged image Noryl is a blend of Polyphenylene oxide (PPO and Polystyrene that was developed by General Electric Plastics in 1966 The Tafel equation relates the rate of an electrochemical reaction to the Overpotential. Hot cathode is also a name for a Hot filament ionization gauge, a vacuum measuring device A cold cathode is an element used within some Nixie tubes Gas discharge lamps Gas filled tubes and Vacuum tubes Cold cathodes do not Year 1834 ( MDCCCXXXIV) was a Common year starting on Wednesday (link will display the full calendar of the Gregorian Calendar (or a Common An anode is an Electrode through which Electric current flows into a polarized electrical device A cathode is an Electrode through which (positive Electric current flows out of a polarized electrical device An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge An electrolyte is any substance containing free Ions that behaves as an electrically conductive medium In chemistry and manufacturing electrolysis is a method of separating chemically bonded elements and compounds by passing an Electric current

Dictionary

electrode

-noun

  1. the terminal through which electric current passes between metallic and nonmetallic parts of an electric circuit
  2. a collector or emitter of electric charge in a semiconducting device
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