Editing Michael Faraday (section)

==Scientific achievements==
===Chemistry===
[[File:Ri 2014 - glass making - Faraday.jpg|thumb|left|upright=0.80|Equipment used by Faraday to make glass on display at the [[Royal Institution]] in London]]
Faraday's earliest chemical work was as an assistant to [[Humphry Davy]]. Faraday was involved in the study of [[chlorine]]; he discovered two new compounds of chlorine and [[carbon]]:  [[hexachloroethane]] which he made via the chlorination of [[ethylene]] and [[carbon tetrachloride]] from the decomposition of the former. He also conducted the first rough experiments on the diffusion of gases, a phenomenon that was first pointed out by [[John Dalton]]. The physical importance of this phenomenon was more fully revealed by [[Thomas Graham (chemist)|Thomas Graham]] and [[Joseph Loschmidt]]. Faraday succeeded in liquefying several gases, investigated the alloys of steel, and produced several new kinds of glass intended for optical purposes. A specimen of one of these heavy glasses subsequently became historically important; when the glass was placed in a magnetic field Faraday determined the rotation of the plane of polarisation of light. This specimen was also the first substance found to be repelled by the poles of a magnet.<ref>{{cite journal |last1=Hadfield |first1=Robert Abbott |title=A research on Faraday's 'steel and alloys' |journal=Philosophical Transactions of the Royal Society of London. Series A, Containing Papers of a Mathematical or Physical Character |date=1931 |volume=230 |issue=681–693 |pages=221–292 |doi=10.1098/rsta.1932.0007 |doi-access=free }}</ref><ref>{{cite web |last1=Akerlof |first1=Carl W. |title=Faraday Rotation |url=http://instructor.physics.lsa.umich.edu/adv-labs/Faraday/Faraday_Effect-july09-5.pdf |access-date=29 November 2023}}</ref>

Faraday invented an early form of what was to become the [[Bunsen burner]], which is still in practical use in science laboratories around the world as a convenient source of heat.<ref>{{Cite journal|author1-link=William B. Jensen| last =Jensen  | first =William B. |doi=10.1021/ed082p518 | title =The Origin of the Bunsen Burner | journal=[[Journal of Chemical Education]]  | volume = 82  | issue = 4 | page =518 | year =2005  | url = http://jchemed.chem.wisc.edu/HS/Journal/Issues/2005/Apr/clicSubscriber/V82N04/p518.pdf |archive-url=https://web.archive.org/web/20050530143615/http://jchemed.chem.wisc.edu/HS/Journal/Issues/2005/Apr/clicSubscriber/V82N04/p518.pdf |archive-date=30 May 2005 |bibcode = 2005JChEd..82..518J }}</ref><ref>[[#Faraday1827|Faraday (1827)]], p. 127.</ref>
Faraday worked extensively in the field of chemistry, discovering chemical substances such as [[benzene]] (which he called bicarburet of hydrogen) and liquefying gases such as chlorine. The liquefying of gases helped to establish that gases are the vapours of liquids possessing a very low boiling point and gave a more solid basis to the concept of molecular aggregation. In 1820 Faraday reported the first synthesis of compounds made from carbon and chlorine, [[hexachloroethane|C<sub>2</sub>Cl<sub>6</sub>]] and [[carbon tetrachloride|CCl<sub>4</sub>]], and published his results the following year.<ref>{{Cite journal| author=Faraday, Michael | title = On two new Compounds of Chlorine and Carbon, and on a new Compound of Iodine, Carbon, and Hydrogen | journal=Philosophical Transactions | year = 1821 | volume = 111| pages = 47–74 | doi = 10.1098/rstl.1821.0007 | s2cid = 186212922 | doi-access =  }}</ref><ref>{{Cite book| last = Faraday | first = Michael | title = Experimental Researches in Chemistry and Physics | publisher=[[Richard Taylor and William Francis]] | year= 1859 | location = London | pages = 33–53| isbn = 978-0-85066-841-4}}</ref><ref>{{Cite book | last = Williams | first = L. Pearce | title = Michael Faraday: A Biography | publisher = [[Basic Books]] | year = 1965 | location = New York | pages = [https://archive.org/details/michaelfaradaybi0000will_g3v0/page/122 122–123] | isbn = 978-0-306-80299-7 | url = https://archive.org/details/michaelfaradaybi0000will_g3v0/page/122 }}</ref> Faraday also determined the composition of the chlorine [[clathrate hydrate]], which had been discovered by Humphry Davy in 1810.<ref>{{Cite journal| author=Faraday, Michael | title = On Hydrate of Chlorine |url=https://books.google.com/books?id=lhw_AAAAYAAJ&pg=PA71| journal=Quarterly Journal of Science | year = 1823 | volume = 15| page = 71 }}</ref><ref>{{Cite book| last = Faraday | first = Michael | title = Experimental Researches in Chemistry and Physics | publisher=Richard Taylor and William Francis | year= 1859 | location = London | pages = 81–84| isbn = 978-0-85066-841-4}}</ref> Faraday is also responsible for discovering the [[Faraday's laws of electrolysis|laws of electrolysis]], and for popularising terminology such as [[anode]], [[cathode]], [[electrode]], and [[ion]], terms proposed in large part by [[William Whewell]].<ref>{{cite journal | author = Ehl, Rosemary Gene |author2=Ihde, Aaron |url=http://www.elch.chem.msu.ru/rus/wp/wp-content/uploads/2016/03/ed031p226FaradayLaw.pdf | title = Faraday's Electrochemical Laws and the Determination of Equivalent Weights | journal = Journal of Chemical Education | year = 1954 | volume = 31 | issue = May | pages = 226–232 | doi = 10.1021/ed031p226 | bibcode=1954JChEd..31..226E}}</ref>

Faraday was the first to report what later came to be called metallic [[nanoparticles]]. In 1847 he discovered that the optical properties of gold [[colloid]]s differed from those of the corresponding bulk metal. This was probably the first reported observation of the effects of [[quantum]] size, and might be considered to be the birth of [[nanoscience]].<ref>{{Cite web|url=http://www.nanogallery.info/nanogallery/?ipg=126 |title=The Birth of Nanotechnology |access-date=25 July 2007 |year=2006 |publisher=Nanogallery.info |quote=Faraday made some attempt to explain what was causing the vivid coloration in his gold mixtures, saying that known phenomena seemed to indicate that a mere variation in the size of gold particles gave rise to a variety of resultant colors. }}</ref>

===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>

===Diamagnetism===
[[File:Faraday with glass bar crop2.jpg|thumb|upright|Faraday holding a type of glass bar he used in 1845 to show magnetism affects light in [[dielectric]] material<ref>{{cite web|title=Detail of an engraving by Henry Adlard, based on earlier photograph by Maull & Polyblank ''ca.'' 1857|url=http://www.npg.org.uk/live/search/person.asp?LinkID=mp01529|publisher=[[NPR]]|location=National Portrait Gallery, UK}}</ref>]]
In 1845, Faraday discovered that many materials exhibit a weak repulsion from a magnetic field: an effect he termed [[diamagnetism]].<ref>James, Frank A.J.L (2010). ''Michael Faraday: A Very Short Introduction''. Oxford University Press. {{ISBN|0-19-161446-7}}. p. 81.</ref>

Faraday also discovered that the plane of [[Polarization (waves)|polarization]] of linearly polarised light can be rotated by the application of an external magnetic field aligned with the direction in which the light is moving. This is now termed the [[Faraday effect]].<ref name="Pioneers"/> In Sept 1845 he wrote in his notebook, "I have at last succeeded in ''illuminating a magnetic curve'' or ''[[line of force]]'' and in ''magnetising a [[Ray (optics)|ray of light]]''".<ref>Day, Peter (1999). ''The Philosopher's Tree: A Selection of Michael Faraday's Writings''. CRC Press. {{ISBN|0-7503-0570-3}}. p. 125.</ref>

Later on in his life, in 1862, Faraday used a spectroscope to search for a different alteration of light, the change of spectral lines by an applied magnetic field. The equipment available to him was, however, insufficient for a definite determination of spectral change. [[Pieter Zeeman]] later used an improved apparatus to study the same phenomenon, publishing his results in 1897 and receiving the 1902 Nobel Prize in Physics for his success. In both his 1897 paper<ref>{{Cite journal| title = The Effect of Magnetisation on the Nature of Light Emitted by a Substance | journal=[[Nature (journal)|Nature]]  | year = 1897 | volume = 55 | page = 347 | author=Zeeman, Pieter | doi = 10.1038/055347a0|bibcode = 1897Natur..55..347Z | issue=1424| doi-access = free }}</ref> and his Nobel acceptance speech, Zeeman made reference to Faraday's work.<ref>{{Cite web| title = Pieter Zeeman, Nobel Lecture | url = http://nobelprize.org/nobel_prizes/physics/laureates/1902/zeeman-lecture.html | access-date =29 May 2008}}</ref>

====Faraday cage====
In his work on static electricity, [[Faraday's ice pail experiment]] demonstrated that the charge resided only on the exterior of a charged conductor, and exterior charge had no influence on anything enclosed within a conductor. This is because the exterior charges redistribute such that the interior fields emanating from them cancel one another. This shielding effect is used in what is now known as a [[Faraday cage]].<ref name="Pioneers"/> In January 1836, Faraday had put a wooden frame, 12&nbsp;ft square, on four glass supports and added paper walls and wire mesh. He then stepped inside and electrified it. When he stepped out of his electrified cage, Faraday had shown that electricity was a force, not an imponderable fluid as was believed at the time.<ref name="Field"/>