Michael Faraday: Difference between revisions
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'''Michael Faraday''' (22 September 1791 – 25 August 1867) was an English physicist and chemist. In 1821, soon after [[Hans Christian Oersted|Oersted]]'s discovery, he published his work on—what he called—electromagnetic rotation (the principle behind the electric motor). In 1831, Faraday discovered electromagnetic induction, the principle behind the electric transformer and electric generator. In chemistry Faraday discovered [[benzene]], contributed importantly to [[electrochemistry]], and popularized terminology such as [[anode]], [[cathode]], [[electrode]], and [[ion]]. | '''Michael Faraday''' (22 September 1791 – 25 August 1867) was an English physicist and chemist. In 1821, soon after [[Hans Christian Oersted|Oersted]]'s discovery, he published his work on—what he called—electromagnetic rotation (the principle behind the electric motor). In 1831, Faraday discovered electromagnetic induction, the principle behind the electric transformer and electric generator. In chemistry Faraday discovered [[benzene]], contributed importantly to [[electrochemistry]], and popularized terminology such as [[anode]], [[cathode]], [[electrode]], and [[ion]]. | ||
==Biography== | |||
==Faraday's science== | |||
===Faraday's contributions to electromagnetism=== | |||
[[Image:Faraday electromagnetic rotation.jpg|right|thumb|350px|{{#ifexist:Template:Faraday electromagnetic rotation.jpg/credit|{{Faraday electromagnetic rotation.jpg/credit}}<br/>|}}Adaptation of Faraday's illustration of his apparatus for electromagnetic rotation. The vessels are filled with mercury (grey), current runs through copper wires (red) and the bar magnets, floating on the left and fixed on the right, are blue.]] | |||
When Faraday heard of [[Oersted]]'s discovery (1820) that a steady electric current in a wire generates a circular magnetic field (with the current-carrying wire the center of the field), it occurred to him that a magnetic pole would be pushed around a circle by such a field and hence would rotate forever, or at least as long as the current is running. In 1821 he designed the apparatus shown in the figure on the right.<ref>M. Faraday, ''Experimental researches in electricity'', vol II, | |||
Richard and John Edward Taylor, London (1844). Plate IV [http://gallica.bnf.fr/ark:/12148/bpt6k94884v/f318.table On line] </ref> | |||
In the vessel on the left a strong bar magnet floats in mercury held in place only by a thread at its bottom. Recall that mercury is a heavy liquid that is a very good conductor of electricity. A fixed cupper wire is dipped into the mercury. At the bottom of the vessel a wire sticks into the mercury. In the vessel on the right a bar magnet is fixed in a conducting (copper) socket that extends into the bath and a copper wire that hangs from a kind of ball bearing is dipped into the mercury. When a direct current is switched on (running through the wires and the mercury baths) the wire on the right rotates around the magnet so fast that—as described by Faraday—the eye can scarcely follow the motion. The magnet on the left rotates around the fixed wire. Note that Faraday's setup is such that only one pole of the two poles of the magnets is involved. If the magnets are turned around (i.e., the North and South poles are interchanged) the rotation of the wire and the magnet changes direction. The same happens if the current runs in opposite direction. Faraday, who coined the term ''electromagnetic rotation'' for this effect, had in fact invented the [[electric motor]]. | |||
==References== | |||
<references /> | |||
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Revision as of 17:16, 5 April 2008
Michael Faraday (22 September 1791 – 25 August 1867) was an English physicist and chemist. In 1821, soon after Oersted's discovery, he published his work on—what he called—electromagnetic rotation (the principle behind the electric motor). In 1831, Faraday discovered electromagnetic induction, the principle behind the electric transformer and electric generator. In chemistry Faraday discovered benzene, contributed importantly to electrochemistry, and popularized terminology such as anode, cathode, electrode, and ion.
Biography
Faraday's science
Faraday's contributions to electromagnetism
When Faraday heard of Oersted's discovery (1820) that a steady electric current in a wire generates a circular magnetic field (with the current-carrying wire the center of the field), it occurred to him that a magnetic pole would be pushed around a circle by such a field and hence would rotate forever, or at least as long as the current is running. In 1821 he designed the apparatus shown in the figure on the right.[1] In the vessel on the left a strong bar magnet floats in mercury held in place only by a thread at its bottom. Recall that mercury is a heavy liquid that is a very good conductor of electricity. A fixed cupper wire is dipped into the mercury. At the bottom of the vessel a wire sticks into the mercury. In the vessel on the right a bar magnet is fixed in a conducting (copper) socket that extends into the bath and a copper wire that hangs from a kind of ball bearing is dipped into the mercury. When a direct current is switched on (running through the wires and the mercury baths) the wire on the right rotates around the magnet so fast that—as described by Faraday—the eye can scarcely follow the motion. The magnet on the left rotates around the fixed wire. Note that Faraday's setup is such that only one pole of the two poles of the magnets is involved. If the magnets are turned around (i.e., the North and South poles are interchanged) the rotation of the wire and the magnet changes direction. The same happens if the current runs in opposite direction. Faraday, who coined the term electromagnetic rotation for this effect, had in fact invented the electric motor.