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Encyclopedia > Electrodes
Alternative meanings: There is also an Electric-type Pokémon named Electrode.

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].


Anode vs. 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 oxidation occurs, and the cathode is defined as the electrode at which reduction occurs. Each electrode may become either the anode or the cathode depending on the type of reaction occurring in the 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 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.

Other uses of anode and cathode

In a vacuum tube or a semiconductor having polarity (diodes, electrolytic capacitors) the anode is the positive (+) electrode and the cathode the negative (-).

Types of electrode

Related topics


Michael Faraday, "On Electrical Decomposition (http://dbhs.wvusd.k12.ca.us/Chem-History/Faraday-electrochem.html)", Philosophical Transactions of the Royal Society, 1834 (in which Faraday coins the words electrode, anode, cathode, anion, cation, electrolyte, electrolyze).

  Results from FactBites:
Electrode - Wikipedia, the free encyclopedia (542 words)
A bipolar electrode is an electrode that functions as the anode of one cell and the cathode of another cell.
In a vacuum tube or a semiconductor having polarity (diodes, electrolytic capacitors) the anode is the positive (+) electrode and the cathode the negative (−).
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.
Electrochemistry Dictionary (11199 words)
An electrode that is shared by two series-coupled electrochemical cells in such a way that one side of the (usually planar) electrode acts as an anode in one cell and the other side acts as a cathode in the other cell.
In case of an electrode reaction, the electrode itself is considered one of the "reactants." An electrode reaction is a heterogeneous charge-transfer reaction.
An electrode reaction is considered to be under “diffusion control” when the overall rate of the reaction is is controlled by the rate of the diffusion of the reactants to the electrode surface rather than the rate of the reaction itself.
  More results at FactBites »



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