Editing Michael Faraday (section)

===Electricity and magnetism===
Faraday is best known for his work on electricity and magnetism. His first recorded experiment was the construction of a [[voltaic pile]] with seven [[Halfpenny (British pre-decimal coin)|British halfpenny]] coins, stacked together with seven discs of sheet zinc, and six pieces of paper moistened with salt water.<ref name="First experiment"/> With this pile he passed the [[electric current]] through a solution of [[Magnesium sulfate|sulfate of magnesia]] and succeeded in decomposing the chemical compound (recorded in first letter to Abbott, 12 July 1812).<ref name="First experiment">{{cite book |last1=Mee |first1=Nicholas |title=Higgs Force: The Symmetry-breaking Force that Makes the World an Interesting Place |date=2012 |page=55}}</ref>

[[File:Faraday magnetic rotation.jpg|thumb|left|upright|Electromagnetic rotation experiment of Faraday, 1821,  the first demonstration of the conversion of electrical energy into motion<ref>{{Cite book| author=Faraday, Michael | title = Experimental Researches in Electricity | year = 1844 | volume = 2| publisher = Courier Corporation | isbn = 978-0-486-43505-3 }} See plate 4.</ref>]]
In 1821, soon after the Danish physicist and chemist [[Hans Christian Ørsted]] discovered the phenomenon of [[electromagnetism]], Davy and [[William Hyde Wollaston]] tried, but failed, to design an [[electric motor]].<ref name="IEEUK"/> Faraday, having discussed the problem with the two men, went on to build two devices to produce what he called "electromagnetic rotation". One of these, now known as the [[homopolar motor]], caused a continuous circular motion that was engendered by the circular magnetic force around a wire that extended into a pool of [[mercury (element)|mercury]] wherein was placed a magnet; the wire would then rotate around the magnet if supplied with current from a chemical battery. These experiments and inventions formed the foundation of modern electromagnetic technology. In his excitement, Faraday published results without acknowledging his work with either Wollaston or Davy. The resulting controversy within the [[Royal Society]] strained his mentor relationship with Davy and may well have contributed to Faraday's assignment to other activities, which consequently prevented his involvement in electromagnetic research for several years.<ref>[[#Hamilton|Hamilton]], pp. 165–171, 183, 187–190.</ref><ref>[[#Cantor|Cantor]], pp. 231–233.</ref>

[[File:Induction experiment.png|thumb|One of Faraday's 1831 experiments demonstrating induction. The liquid battery ''(right)'' sends an electric current through the small coil ''(A)''.  When it is moved in or out of the large coil ''(B)'', its magnetic field induces a momentary voltage in the coil, which is detected by the galvanometer ''(G)''.]]
From his initial discovery in 1821, Faraday continued his laboratory work, exploring electromagnetic properties of materials and developing requisite experience. In 1824, Faraday briefly set up a circuit to study whether a magnetic field could regulate the flow of a current in an adjacent wire, but he found no such relationship.<ref>[[#Thompson|Thompson]], p. 95.</ref> This experiment followed similar work conducted with light and magnets three years earlier that yielded identical results.<ref>[[#Thompson|Thompson]], p. 91. This lab entry illustrates Faraday's quest for the connection between light and electromagnetic phenomenon 10 September 1821.</ref><ref>[[#Cantor|Cantor]], p. 233.</ref> During the next seven years, Faraday spent much of his time perfecting his recipe for optical quality (heavy) glass, borosilicate of lead,<ref>[[#Thompson|Thompson]], pp. 95–98.</ref> which he used in his future studies connecting light with magnetism.<ref>[[#Thompson|Thompson]], p. 100.</ref>  In his spare time, Faraday continued publishing his experimental work on optics and electromagnetism; he conducted correspondence with scientists whom he had met on his journeys across Europe with Davy, and who were also working on electromagnetism.<ref>Faraday's initial induction lab work occurred in late November 1825. His work was heavily influenced by the ongoing research of fellow European scientists Ampere, Arago, and Oersted as indicated by his diary entries. [[#Cantor|Cantor]], pp. 235–244.</ref> Two years after the death of Davy, in 1831, he began his great series of experiments in which he discovered [[electromagnetic induction]], recording in his laboratory diary on 28 October 1831 that he was "making many experiments with the great magnet of the Royal Society".<ref>Gooding, David; Pinch, Trevor; Schaffer, Simon (1989). ''The Uses of Experiment: Studies in the Natural Sciences''. Cambridge University Press. {{ISBN|0-521-33768-2}}. p. 212.</ref>

[[File:Faraday emf experiment.svg|thumb|A diagram of Faraday's iron ring-coil apparatus]]
[[File:Faraday disk generator.jpg|thumb|left|upright|Built in 1831, the [[Faraday disc]] was the first [[electric generator]]. The horseshoe-shaped magnet ''(A)'' created a magnetic field through the disc ''(D)''. When the disc was turned, this induced an electric current radially outward from the centre toward the rim.  The current flowed out through the sliding spring contact ''m'', through the external circuit, and back into the centre of the disc through the axle.]]
Faraday's breakthrough came when he wrapped two insulated coils of wire around an iron ring, and found that, upon passing a current through one coil, a momentary current was induced in the other coil.<ref name="IEEUK"/> This phenomenon is now known as [[mutual inductance]].<ref>Van Valkenburgh (1995). ''Basic Electricity''. Cengage Learning. {{ISBN|0-7906-1041-8}}. pp.&nbsp;4–91.</ref> The iron ring-coil apparatus is still on display at the Royal Institution. In subsequent experiments, he found that if he moved a magnet through a loop of wire an electric current flowed in that wire. The current also flowed if the loop was moved over a stationary magnet. His demonstrations established that a changing magnetic field produces an electric field; this relation was modelled mathematically by [[James Clerk Maxwell]] as [[Faraday's law of induction|Faraday's law]], which subsequently became one of the four [[Maxwell's equations|Maxwell equations]], and which have in turn evolved into the generalization known today as [[Field theory (physics)|field theory]].<ref name="Pioneers"/> Faraday would later use the principles he had discovered to construct the electric [[dynamo]], the ancestor of modern power generators and the electric motor.<ref>{{cite news|title=Michael Faraday's generator|url=http://www.rigb.org/our-history/iconic-objects/iconic-objects-list/faraday-generator|publisher=The Royal Institution|date=15 October 2017}}</ref>

[[File:Faraday and Daniell.jpg|thumb|upright|Faraday (right) and [[John Frederic Daniell|John Daniell]] (left), founders of electrochemistry]]
In 1832, he completed a series of experiments aimed at investigating the fundamental nature of electricity; Faraday used "[[Electrostatics|static]]", [[Battery (electricity)|batteries]], and "[[Bioelectromagnetism|animal electricity]]" to produce the phenomena of electrostatic attraction, [[electrolysis]], [[Electromagnetism|magnetism]], etc. He concluded that, contrary to the scientific opinion of the time, the divisions between the various "kinds" of electricity were illusory. Faraday instead proposed that only a single "electricity" exists, and the changing values of quantity and intensity (current and voltage) would produce different groups of phenomena.<ref name="IEEUK"/>

Near the end of his career, Faraday proposed that electromagnetic forces extended into the empty space around the conductor.<ref name="Pioneers">{{cite book|title=Lives and Times of Great Pioneers in Chemistry (lavoisier to Sanger)|date=2015|publisher=World Scientific|pages=85, 86}}</ref> This idea was rejected by his fellow scientists, and Faraday did not live to see the eventual acceptance of his proposition by the scientific community. It would be another half a century before electricity was used in technology, with the [[West End theatre|West End]]'s [[Savoy Theatre]], fitted with the [[incandescent light bulb]] developed by Sir [[Joseph Swan]], the first public building in the world to be lit by electricity.<ref>"The Savoy Theatre", ''[[The Times]]'', 3 October 1881. "An interesting experiment was made at a performance of ''Patience'' yesterday afternoon, when the stage was for the first time lit up by the electric light, which has been used in the auditorium ever since the opening of the Savoy Theatre. The success of the new mode of illumination was complete, and its importance for the development of scenic art can scarcely be overrated. The light was perfectly steady throughout the performance, and the effect was pictorially superior to gas, the colours of the dresses – an important element in the "æsthetic" opera – appearing as true and distinct as by daylight. The Swan incandescent lamps were used, the aid of gaslight being entirely dispensed with".</ref><ref>{{cite news |title=The Savoy is one of the best places to stay in London |url=https://10best.usatoday.com/destinations/uk-england/london/london/hotels/the-savoy-1/ |access-date=6 July 2024 |work=USA Today |quote=The first public building in the world to be lit entirely by electricity, The Savoy has a history rich in both invention and scandal.}}</ref> As recorded by the [[Royal Institution]], "Faraday invented the generator in 1831 but it took nearly 50 years before all the technology, including Joseph Swan's incandescent filament light bulbs used here, came into common use".<ref>{{cite news |title=A tour of Michael Faraday in London |url=https://www.rigb.org/explore-science/explore/collection/tour-michael-faraday-london |access-date=6 July 2024 |work=[[The Royal Institution]]}}</ref>