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A galvanic cell, or voltaic cell, named after Luigi Galvani, or Alessandro Volta respectively, is an electrochemical cell that derives electrical energy from spontaneous redox reactions taking place within the cell. It generally consists of two different metals connected by a salt bridge, or individual half-cells separated by a porous membrane. Volta was the inventor of the voltaic pile, the first electrical battery. In common usage, the word "battery" has come to include a single galvanic cell, but a battery properly consists of multiple cells.〔("battery" (def. 4b) ), ''Merriam-Webster Online Dictionary'' (2008). Retrieved 6 August 2008.〕 ==History== In 1780, Luigi Galvani discovered that when two different metals (e.g., copper and zinc) are connected and then both touched at the same time to two different parts of a nerve of a frog leg, then the leg contracts. He called this "animal electricity". The voltaic pile, invented by Alessandro Volta in the 1800s, consists of a pile of cells similar to the galvanic cell. However, Volta built it entirely out of non-biological material in order to challenge Galvani's (and the later experimenter Leopoldo Nobili) animal electricity theory in favour of his own metal-metal contact electricity theory.〔Kipnis, Nahum (2003) ("Changing a theory: the case of Volta's contact electricity" ), ''Nuova Voltiana'', Vol. 5. Università degli studi di Pavia, 2003 ISBN 88-203-3273-6. pp. 144–146〕 Carlo Matteucci in his turn constructed a battery entirely out of biological material in answer to Volta.〔Clarke, Edwin; Jacyna, L. S. (1992) (''Nineteenth-Century Origins of Neuroscientific Concepts'' ), University of California Press. ISBN 0-520-07879-9. p. 199〕 These discoveries paved the way for electrical batteries; Volta's cell was named an IEEE Milestone in 1999. It was suggested by Wilhelm König in 1940 that the object known as the Baghdad battery might represent galvanic cell technology from ancient Parthia. Replicas filled with citric acid or grape juice have been shown to produce a voltage. However, it is far from certain that this was its purpose—other scholars have pointed out that it is very similar to vessels known to have been used for storing parchment scrolls.〔Haughton, Brian (2007) ''Hidden History: Lost Civilizations, Secret Knowledge, and Ancient Mysteries''. Career Press. ISBN 1564148971. pp. 129–132〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「galvanic cell」の詳細全文を読む スポンサード リンク
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