Gustav Kirchhoff: Difference between revisions

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{{Short description|German chemist, mathematician, physicist, and spectroscopist (1824–1887)}}
{{Short description|German physicist and mathematician (1824–1887)}}
{{Use dmy dates|date=February 2021}}
{{Use dmy dates|date=February 2021}}
{{Infobox scientist
{{Infobox scientist
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| birth_place      = [[Königsberg]], [[East Prussia]], [[Kingdom of Prussia]]
| birth_place      = [[Königsberg]], [[East Prussia]], [[Kingdom of Prussia]]
| death_date        = {{Death date and age|1887|10|17|1824|03|12|df=yes}}
| death_date        = {{Death date and age|1887|10|17|1824|03|12|df=yes}}
| death_place      = Berlin, [[German Empire]]
| death_place      = [[Berlin]], [[German Empire]]
| resting_place    = [[Alter St.-Matthäus-Kirchhof]], Berlin
| resting_place    = ''[[Alter St.-Matthäus-Kirchhof]]'', Berlin
| alma_mater        = [[University of Königsberg]]
| alma_mater        = [[University of Königsberg]] ([[Dr. phil.]])
| known_for        = {{Plain list|
| known_for        = {{Plain list|
* [[Kirchhoff's circuit laws]] (1845)
* [[Kirchhoff's law of thermal radiation]]
* [[Kirchhoff's law of thermal radiation]] (1860)
* [[Kirchhoff's circuit laws]]
* Discovering [[caesium]] (1860)
* [[Kirchhoff's theorem]]
* Discovering [[rubidium]] (1861)
* [[Kirchhoff's diffraction formula]]
* Discovering [[caesium]] and [[rubidium]]
}}
}}
| spouses          = {{Plain list|
| spouses          = {{Plain list|
* {{Marriage|Clara Richelot|1857|1869|reason=died}}
* {{Marriage|Clara Richelot|1857|1869|end=died}}
* {{Marriage|Luise Brömmel|1872}}
* {{Marriage|Luise Brömmel|1872}}
}}
}}
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* [[Matteucci Medal]] (1877)
* [[Matteucci Medal]] (1877)
* [[Davy Medal]] (1877)
* [[Davy Medal]] (1877)
* [[Janssen Medal (French Academy of Sciences)|Janssen Medal]] (1887){{cn|date=May 2025}}
* [[Janssen Medal (French Academy of Sciences)|Janssen Medal]] (1887)
}}
| honors            = [[File:D-PRU Pour le Merite 1 BAR.svg|25px]] ''[[Pour le Mérite#Civil class|Pour le Mérite]]'' (1874)
| fields            = {{Flat list|
* [[Chemistry]]
* [[mathematics]]
* [[physics]]
* [[spectroscopy]]
}}
}}
| fields            = [[Thermodynamics]], [[electromagnetism]], <br/> [[graph theory]], [[optics]], [[spectroscopy]]
| work_institutions = {{Plain list|
| work_institutions = {{Plain list|
* [[University of Berlin]] <br/> (from 1847, 1875–1887)
* [[University of Berlin]] (1847–1850, 1875–1887)
* [[University of Breslau]] <br/> (until 1854)
* [[University of Breslau]] (1850–1854)
* [[University of Heidelberg]] <br/> (1854–1875)
* [[University of Heidelberg]] (1854–1875)
}}
}}
| academic_advisors = {{Plain list|
| thesis_title      = Ueber den Durchgang eines elektrischen Stromes durch eine Ebene, insbesondere durch eine kreisförmige
* [[Carl Gustav Jacob Jacobi]]
| thesis_url        = https://zenodo.org/records/2422851
* [[Franz Ernst Neumann]]
| thesis_year      = 1847
* [[Friedrich Julius Richelot]]
| doctoral_advisor  = [[Franz Ernst Neumann]]
}}
| notable_students  = {{Collapsible list|title={{Nobold|''See list''}}
| doctoral_students = {{Plain list|
| [[Hermann Aron]]<ref name=MGP>{{Cite web|title=Gustav Kirchhoff - The Mathematics Genealogy Project|url=https://www.genealogy.math.ndsu.nodak.edu/id.php?id=46968|website=genealogy.math.ndsu.nodak.edu|access-date=2025-10-15}}</ref>
* [[Gabriel Lippmann]] (1874)
| [[Ivan Borgman]]<ref name=PhysicsTree>{{Cite web|title=Gustav Robert Kirchhoff - Physics Tree|url=https://academictree.org/physics/peopleinfo.php?pid=25612|website=academictree.org|access-date=2025-10-15}}</ref>
* [[Heinrich Hertz]] (1880){{cn|date=May 2025}}
| [[Siegfried Czapski]]<ref name=PhysicsTree/>
}}
| [[Loránd Eötvös]]<ref name=MGP/>
| notable_students = {{Plain list|
| [[Heinrich Hertz]]<ref name=PhysicsTree/>
* [[Sofia Kovalevskaya]]
| [[Heike Kamerlingh Onnes]]<ref name=PhysicsTree/>
* [[Arthur Schuster]]
| [[Viktor Kirpichov]]<ref name=MGP/>
* [[Loránd Eötvös]]
| [[Johannes Knoblauch]]<ref name=MGP/>
* [[Edward Leamington Nichols]]
  | [[Sofia Kovalevskaya]]<ref name=PhysicsTree/>
* [[Max Noether]]
| [[Gabriel Lippmann]]<ref name=MGP/>
* [[Heike Kamerlingh Onnes]]
| [[Jacob Lüroth]]<ref name=MGP/>
* [[Max Planck]]
| [[Edward Leamington Nichols]]<ref name=PhysicsTree/>
* [[Ernst Schröder (mathematician)|Ernst Schröder]]{{cn|date=May 2025}}
| [[Max Noether]]<ref name=MGP/>
| [[Karol Olszewski]]<ref name=PhysicsTree/>
| [[Max Planck]]<ref name=PhysicsTree/>
| [[Ernst Schröder (mathematician)|Ernst Schröder]]<ref name=MGP/>
| [[Arthur Schuster]]<ref name=MGP/>
| [[August Witkowski]]<ref name=PhysicsTree/>
| [[Heinrich Martin Weber]]<ref name=MGP/>
| [[Arthur Williams Wright]]<ref name=PhysicsTree/>
}}
}}
}}
}}


'''Gustav Robert Kirchhoff''' ({{IPA|de|ˈgʊstaːf ˈʁoːbɛʁt ˈkɪʁçhɔf|lang}}; 12 March 1824 – 17 October 1887) was a German [[chemist]], [[mathematician]], [[physicist]], and [[spectroscopist]] who contributed to the fundamental understanding of [[electrical circuit]]s, [[spectroscopy]] and the emission of [[black-body radiation]] by heated objects.<ref name="Marshall">{{cite journal |last1=Marshall |first1=James L. |last2=Marshall |first2=Virginia R. |title=  Rediscovery of the Elements: Mineral Waters and Spectroscopy |journal=The Hexagon |date=2008 |pages=42–48 |url=http://www.chem.unt.edu/~jimm/REDISCOVERY%207-09-2018/Hexagon%20Articles/bunsen%20and%20spectroscopy.pdf |access-date=31 December 2019}}</ref><ref>{{Cite book |url=https://books.google.com/books?id=8qHGRTC7h-MC&pg=PT79 |title=An Introduction to Electrical Science |last=Waygood |first=Adrian |date=19 June 2013 |publisher=Routledge |isbn=9781135071134 |language=en }}</ref> He also coined the term ''[[black body]]'' in 1860.<ref>{{Cite book |last=Schmitz |first=Kenneth S. |title=Physical Chemistry |publisher=Elsevier |year=2018 |isbn=9780128005996 |pages=278}}</ref>
'''Gustav Robert Kirchhoff''' ({{IPA|de|ˈgʊstaːf ˈʁoːbɛʁt ˈkɪʁçhɔf|lang}}; 12 March 1824 – 17 October 1887) was a German [[physicist]] and [[mathematician]] who contributed to the fundamental understanding of [[electrical circuit]]s, [[spectroscopy]], and the emission of [[black-body radiation]] by heated objects.<ref name="Marshall">{{cite journal |last1=Marshall |first1=James L. |last2=Marshall |first2=Virginia R. |title=  Rediscovery of the Elements: Mineral Waters and Spectroscopy |journal=The Hexagon |date=2008 |pages=42–48 |url=http://www.chem.unt.edu/~jimm/REDISCOVERY%207-09-2018/Hexagon%20Articles/bunsen%20and%20spectroscopy.pdf |access-date=31 December 2019}}</ref><ref>{{Cite book |url=https://books.google.com/books?id=8qHGRTC7h-MC&pg=PT79 |title=An Introduction to Electrical Science |last=Waygood |first=Adrian |date=19 June 2013 |publisher=Routledge |isbn=9781135071134 |language=en }}</ref> He coined the term ''[[black body]]'' in 1860.<ref>{{Cite book |last=Schmitz |first=Kenneth S. |title=Physical Chemistry |publisher=Elsevier |year=2018 |isbn=9780128005996 |pages=278}}</ref>


Several different sets of concepts are named "Kirchhoff's laws" after him, which include [[Kirchhoff's circuit laws]], [[Kirchhoff's law of thermal radiation]], and Kirchhoff's law of thermochemistry.
Several different sets of concepts are named "Kirchhoff's laws" after him, which include [[Kirchhoff's circuit laws]], [[Kirchhoff's law of thermal radiation]], [[Kirchhoff's diffraction formula]], and Kirchhoff's law of thermochemistry.


The [[Bunsen–Kirchhoff Award]] for spectroscopy is named after Kirchhoff and his colleague, [[Robert Bunsen]].
The [[Bunsen–Kirchhoff Award]] for spectroscopy is named after Kirchhoff and his colleague, [[Robert Bunsen]].


== Life and work ==
== Biography ==
Gustav Kirchhoff was born on 12 March 1824 in [[Königsberg]], [[Prussia]], the son of Friedrich Kirchhoff, a lawyer, and Johanna Henriette Wittke.<ref>{{Cite book |url=https://books.google.com/books?id=SPU8BQAAQBAJ&pg=PA288 |title=Modern Thermodynamics: From Heat Engines to Dissipative Structures |last1=Kondepudi |first1=Dilip |last2=Prigogine |first2=Ilya |date=5 November 2014 |publisher=John Wiley & Sons |isbn=9781118698709 |pages=288 |language=en }}</ref> His family were [[Lutheranism|Lutherans]] in the [[Evangelical Church of Prussia]]. He graduated from the Albertus [[University of Königsberg]] in 1847 where he attended the mathematico-physical seminar directed by [[Carl Gustav Jacob Jacobi]],<ref>{{cite book |title=The Biographical Encyclopedia of Astronomers |last=Hockey |first=Thomas |date=2009 |publisher=[[Springer Nature]] |isbn=978-0-387-31022-0 |access-date=22 August 2012 |chapter=Kirchhoff, Gustav Robert |chapter-url=http://www.springerreference.com/docs/html/chapterdbid/58778.html |title-link=The Biographical Encyclopedia of Astronomers }}</ref> [[Franz Ernst Neumann]] and [[Friedrich Julius Richelot]]. In the same year, he moved to Berlin, where he stayed until he received a professorship at [[Breslau]]. Later, in 1857, he married Clara Richelot, the daughter of his mathematics professor Richelot. The couple had five children. Clara died in 1869. He married Luise Brömmel in 1872.<ref>{{cite web
Gustav Robert Kirchhoff was born on 12 March 1824 in [[Königsberg]], [[Prussia]], the son of Friedrich Kirchhoff, a lawyer, and Johanna Henriette Wittke.<ref>{{Cite book |url=https://books.google.com/books?id=SPU8BQAAQBAJ&pg=PA288 |title=Modern Thermodynamics: From Heat Engines to Dissipative Structures |last1=Kondepudi |first1=Dilip |last2=Prigogine |first2=Ilya |date=5 November 2014 |publisher=John Wiley & Sons |isbn=9781118698709 |pages=288 |language=en }}</ref> His family were [[Lutheranism|Lutherans]] in the [[Evangelical Church of Prussia]].
 
Kirchhoff studied at the [[University of Königsberg]], where he attended the mathematico-physical seminar directed by [[C. G. J. Jacobi]],<ref>{{cite book |title=The Biographical Encyclopedia of Astronomers |last=Hockey |first=Thomas |date=2009 |publisher=[[Springer Nature]] |isbn=978-0-387-31022-0 |access-date=22 August 2012 |chapter=Kirchhoff, Gustav Robert |chapter-url=http://www.springerreference.com/docs/html/chapterdbid/58778.html |title-link=The Biographical Encyclopedia of Astronomers }}</ref> [[Franz Ernst Neumann]], and [[Friedrich Julius Richelot]]. In 1845, while a student, Kirchhoff formulated [[Kirchhoff's circuit laws|two circuit laws]]—which are now ubiquitous in [[electrical engineering]]. He completed this study as a seminar exercise; it later became his doctoral thesis, supervised by Neumann.
 
In 1847, Kirchhoff graduated from the University of Königsberg and became a ''[[Privatdozent]]'' (unsalaried lecturer) at the [[University of Berlin]], where he stayed until 1850 when he was offered a professorship at the [[University of Breslau]]. In 1854, he was called to the [[University of Heidelberg]], where he collaborated with [[Robert Bunsen]] in spectroscopic work. In 1875, Kirchhoff returned to Berlin, where he remained until his death in 1887.
 
In 1857, Kirchhoff married Clara Richelot, the daughter of his mathematics professor Richelot; the couple had five children. In 1872, after Clara's death in 1869, he married Luise Brömmel.<ref>{{cite web
  | url =http://www.kip.uni-heidelberg.de/oeffwiss/kirchhoff
  | url =http://www.kip.uni-heidelberg.de/oeffwiss/kirchhoff
  | title =Gustav Robert Kirchhoff – Dauerausstellung
  | title =Gustav Robert Kirchhoff – Dauerausstellung
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| quote =Am 16. August 1857 heiratete er Clara Richelot, die Tochter des Königsberger Mathematikers ... Frau Clara starb schon 1869. Im Dezember 1872 heiratete Kirchhoff Luise Brömmel. }}</ref>
| quote =Am 16. August 1857 heiratete er Clara Richelot, die Tochter des Königsberger Mathematikers ... Frau Clara starb schon 1869. Im Dezember 1872 heiratete Kirchhoff Luise Brömmel. }}</ref>


In 1864, Kirchhoff was elected a Member of the [[American Philosophical Society]].<ref>{{Cite web |title=APS Member History |url=https://search.amphilsoc.org/memhist/search?creator=&title=&subject=&subdiv=&mem=&year=1864&year-max=1864&dead=&keyword=&smode=advanced |access-date=2021-04-16 |website=search.amphilsoc.org }}</ref> In 1884, he became a Foreign Member of the [[Royal Netherlands Academy of Arts and Sciences]].<ref>{{cite web |url=http://www.dwc.knaw.nl/biografie/pmknaw/?pagetype=authorDetail&aId=PE00001261 |title=G. R. Kirchhoff (1824–1887) |publisher=[[Royal Netherlands Academy of Arts and Sciences]] |access-date=22 July 2015 }}</ref>
Kirchhoff died on 17 October 1887 in [[Berlin]] at the age of 63. He is buried at ''[[Alter St.-Matthäus-Kirchhof]]'' (Old St. Matthew's Cemetery) in [[Schöneberg]], Berlin (just a few meters from the graves of the [[Brothers Grimm]]).
== Research ==
[[File:Bunsen-Kirchhoff.jpg|thumb|left|upright|Kirchhoff (left) and [[Robert Bunsen]], {{Circa|1850}}|alt= Black-and-white image of two middle-aged men, either one leaning with one elbow on a wooden column in the middle. Both wear long jackets, and the shorter man on the left has a beard.]]  
[[File:Bunsen-Kirchhoff.jpg|thumb|left|upright|Kirchhoff (left) and [[Robert Bunsen]], {{Circa|1850}}|alt= Black-and-white image of two middle-aged men, either one leaning with one elbow on a wooden column in the middle. Both wear long jackets, and the shorter man on the left has a beard.]]  
Kirchhoff formulated [[Kirchhoff's circuit laws|his circuit laws]], which are now ubiquitous in [[electrical engineering]], in 1845, while he was still a student. He completed this study as a seminar exercise; it later became his doctoral dissertation. He was called to the [[University of Heidelberg]] in 1854, where he collaborated in spectroscopic work with [[Robert Bunsen]]. In 1857, he calculated that an electric signal in a [[electrical resistance|resistanceless]] wire travels along the wire at the [[speed of light]].<ref>
 
In 1857, Kirchhoff calculated that an electric signal in a [[electrical resistance|resistanceless]] wire travels along the wire at the [[speed of light]].<ref>
{{cite journal
{{cite journal
  |last=Kirchhoff |first=Gustav
  |last=Kirchhoff |first=Gustav
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  |date=1994
  |date=1994
  |pages=19–25
  |pages=19–25
}}</ref> He proposed his [[Kirchhoff's law of thermal radiation|law of thermal radiation]] in 1859, and gave a proof in 1861. Together Kirchhoff and Bunsen invented the [[spectroscopy|spectroscope]], which Kirchhoff used to pioneer the identification of the [[Sun#Composition|elements in the Sun]], showing in 1859 that the Sun contains [[sodium]]. He and Bunsen discovered [[caesium]] and [[rubidium]] in 1861.<ref name="Weeks">{{cite book |last1=Weeks |first1=Mary Elvira |title=The discovery of the elements |date=1956 |publisher=Journal of Chemical Education |location=Easton, PA |url=https://archive.org/details/discoveryoftheel002045mbp |edition=6th }}</ref> At [[Heidelberg]] he ran a mathematico-physical seminar, modelled on Franz Ernst Neumann's, with the mathematician [[Leo Koenigsberger]]. Among those who attended this seminar were [[Arthur Schuster]] and [[Sofia Kovalevskaya]].
}}</ref>
 
He contributed greatly to the field of [[spectroscopy]] by formalizing three laws that describe the [[optical spectrum|spectral]] composition of [[light]] emitted by incandescent objects, building substantially on the discoveries of [[David Alter]] and [[Anders Jonas Ångström]]. In 1862, he was awarded the [[Rumford Medal]] for his researches on the fixed lines of the solar spectrum, and on the inversion of the bright lines in the spectra of artificial light.{{efn|Kirchhoff's banker, on hearing that Kirchhoff had identified the elements present in the Sun, remarked "of what use is gold in the Sun if it cannot be brought to Earth?" Kirchhoff deposited his prize money (gold sovereigns) with the banker, saying "here is gold from the Sun."<ref>[[Isaac Asimov|Asimov, Isaac]], ''The Secret of the Universe'', Oxford University Press, 1992, p. 109</ref>}} In 1875 Kirchhoff accepted the first chair dedicated specifically to [[theoretical physics]] at Berlin.


He also contributed to [[optics]], carefully solving the [[wave equation]] to provide a solid foundation for [[Huygens' principle]] (and correct it in the process).<ref>Baker, Bevan B.; and Copson, Edward T.; ''The Mathematical Theory of Huygens' Principle'', Oxford University Press, 1939, pp.{{nnbsp}}36–38.</ref><ref name=miller1991>Miller, David A. B.; "Huygens's wave propagation principle corrected", Optics Letters '''16''', 1370–1372, 1991</ref>
In 1859, Kirchhoff proposed [[Kirchhoff's law of thermal radiation|a law of thermal radiation]], and gave a proof in 1861.  


In 1864, he was elected as a member of the [[American Philosophical Society]].<ref>{{Cite web |title=APS Member History |url=https://search.amphilsoc.org/memhist/search?creator=&title=&subject=&subdiv=&mem=&year=1864&year-max=1864&dead=&keyword=&smode=advanced |access-date=2021-04-16 |website=search.amphilsoc.org }}</ref>
Together, Kirchhoff and Bunsen improved on [[Joseph von Fraunhofer]]'s 1814 [[spectroscopy|spectroscope]], which Kirchhoff used to pioneer the identification of the [[Sun#Composition|elements in the Sun]], showing in 1859 that the Sun contains [[sodium]]. Kirchhoff and Bunsen discovered [[caesium]] and [[rubidium]] in 1861.<ref name="Weeks">{{cite book |last1=Weeks |first1=Mary Elvira |title=The discovery of the elements |date=1956 |publisher=Journal of Chemical Education |location=Easton, PA |url=https://archive.org/details/discoveryoftheel002045mbp |edition=6th }}</ref>


In 1884, he became foreign member of the [[Royal Netherlands Academy of Arts and Sciences]].<ref>{{cite web |url=http://www.dwc.knaw.nl/biografie/pmknaw/?pagetype=authorDetail&aId=PE00001261 |title=G. R. Kirchhoff (1824–1887) |publisher=[[Royal Netherlands Academy of Arts and Sciences]] |access-date=22 July 2015 }}</ref>
Kirchhoff contributed greatly to the field of [[spectroscopy]] by formalizing three laws that describe the [[optical spectrum|spectral]] composition of [[light]] emitted by incandescent objects, building substantially on the discoveries of [[David Alter]] and [[Anders Jonas Ångström]]. In 1862, he was awarded the [[Rumford Medal]] "for his researches on the fixed lines of the solar spectrum, and on the inversion of the bright lines in the spectra of artificial light".{{efn|Kirchhoff's banker, on hearing that Kirchhoff had identified the elements present in the Sun, remarked "of what use is gold in the Sun if it cannot be brought to Earth?" Kirchhoff deposited his prize money (gold sovereigns) with the banker, saying "here is gold from the Sun."<ref>[[Isaac Asimov|Asimov, Isaac]], ''The Secret of the Universe'', Oxford University Press, 1992, p. 109</ref>}}


Kirchhoff died in 1887, and was buried in the [[Alter St.-Matthäus-Kirchhof|St Matthäus Kirchhof Cemetery]] in [[Schöneberg]], Berlin (just a few meters from the graves of the [[Brothers Grimm]]). [[Leopold Kronecker]] is buried in the same cemetery.
Kirchhoff also contributed to [[optics]], carefully solving the [[wave equation]] to provide a solid foundation for [[Huygens' principle]] (and correct it in the process).<ref>Baker, Bevan B.; and Copson, Edward T.; ''The Mathematical Theory of Huygens' Principle'', Oxford University Press, 1939, pp.{{nnbsp}}36–38.</ref><ref name=miller1991>Miller, David A. B.; "Huygens's wave propagation principle corrected", Optics Letters '''16''', 1370–1372, 1991</ref>


===Kirchhoff's circuit laws===
=== Kirchhoff's circuit laws ===
{{main|Kirchhoff's circuit laws}}
{{main|Kirchhoff's circuit laws}}
Kirchhoff's first law is that the algebraic sum of currents in a network of conductors meeting at a point (or node) is zero. The second law is that in a closed circuit, the directed sums of the voltages in the system is zero.
Kirchhoff's first law states that at any node in an electrical circuit where current can branch, the sum of the currents leaving the node is equal to the sum of the currents entering the node. The second law states that the algebraic sum of the potential drops along a closed circuit, taken in any direction of flow, is equal to zero.<ref>Corso di Fisicia 2 author Paul A .Tipler</ref>


=== Kirchhoff's three laws of spectroscopy ===
=== Kirchhoff's three laws of spectroscopy ===
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# If light composing a continuous spectrum passes through a cool, low-density gas, the result will be an absorption spectrum.
# If light composing a continuous spectrum passes through a cool, low-density gas, the result will be an absorption spectrum.


Kirchhoff did not know about the existence of [[energy level]]s in atoms. The existence of discrete spectral lines had been known since [[Fraunhofer lines|Fraunhofer]] discovered them in 1814. That the lines formed a discrete mathematical pattern was described by [[Johann Balmer]] in 1885. [[Joseph Larmor]] explained the splitting of the [[spectral line]]s in a [[magnetic field]] known as the [[Zeeman Effect]] by the [[oscillation]] of electrons.<ref>Buchwald, Jed Z.; and Warwick, Andrew; editors; ''Histories of the Electron: The Birth of Microphysics''</ref><ref>{{Citation |last=Larmor |first=Joseph |year=1897 |title=On a Dynamical Theory of the Electric and Luminiferous Medium, Part 3, Relations with material media |journal=Philosophical Transactions of the Royal Society |volume=190 |pages=205–300 |doi=10.1098/rsta.1897.0020|bibcode = 1897RSPTA.190..205L |title-link=s:Dynamical Theory of the Electric and Luminiferous Medium III |doi-access=free }}</ref> These discrete spectral lines were not explained as electron transitions until the [[Bohr model]] of the atom in 1913, which helped lead to [[quantum mechanics]].{{clear}}
Kirchhoff did not know about the existence of [[energy level]]s in atoms. The existence of discrete spectral lines had been known since [[Fraunhofer lines|Fraunhofer]] discovered them in 1814. That the lines formed a discrete mathematical pattern was described by [[Johann Balmer]] in 1885. [[Joseph Larmor]] explained the splitting of the [[spectral line]]s in a [[magnetic field]] known as the [[Zeeman Effect]] by the oscillation of [[electron]]s.<ref>Buchwald, Jed Z.; and Warwick, Andrew; editors; ''Histories of the Electron: The Birth of Microphysics''</ref><ref>{{Citation |last=Larmor |first=Joseph |year=1897 |title=On a Dynamical Theory of the Electric and Luminiferous Medium, Part 3, Relations with material media |journal=Philosophical Transactions of the Royal Society |volume=190 |pages=205–300 |doi=10.1098/rsta.1897.0020|bibcode = 1897RSPTA.190..205L |title-link=s:Dynamical Theory of the Electric and Luminiferous Medium III |doi-access=free }}</ref> These discrete spectral lines were not explained as [[electron transition]]s until the [[Bohr model]] of the atom in 1913, which helped lead to [[quantum mechanics]].{{clear}}


=== Kirchhoff's law of thermal radiation ===
=== Kirchhoff's law of thermal radiation ===
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Integration of this equation permits the evaluation of the heat of reaction at one temperature from measurements at another temperature.<ref>[[Keith J. Laidler|Laidler, Keith J.]]; and Meiser, J. H.; "Physical Chemistry", Benjamin/Cummings 1982, p. 62</ref><ref>[[Peter Atkins|Atkins, Peter]]; and de Paula, J.; "Atkins' Physical Chemistry", W. H. Freeman, 2006 (8th edition), p. 56</ref>
Integration of this equation permits the evaluation of the heat of reaction at one temperature from measurements at another temperature.<ref>[[Keith J. Laidler|Laidler, Keith J.]]; and Meiser, J. H.; "Physical Chemistry", Benjamin/Cummings 1982, p. 62</ref><ref>[[Peter Atkins|Atkins, Peter]]; and de Paula, J.; "Atkins' Physical Chemistry", W. H. Freeman, 2006 (8th edition), p. 56</ref>


===Kirchhoff's theorem in graph theory===
=== Kirchhoff's theorem in graph theory ===
Kirchhoff also worked in the mathematical field of [[graph theory]], in which he proved [[Kirchhoff's theorem|Kirchhoff's matrix tree theorem]].
Kirchhoff also worked in the mathematical field of [[graph theory]], in which he proved [[Kirchhoff's theorem|Kirchhoff's matrix tree theorem]].


==Works==
== Works ==
* {{Cite book|title=Gesammelte Abhandlungen|volume=|publisher=Johann Ambrosius Barth|location=Leipzig|year=1882|language=de|url=https://gutenberg.beic.it/webclient/DeliveryManager?pid=11943571}}
* {{Cite book|title=Gesammelte Abhandlungen|volume=|publisher=Johann Ambrosius Barth|location=Leipzig|year=1882|language=de|url=https://gutenberg.beic.it/webclient/DeliveryManager?pid=11943571}}
* {{Cite book|title=Vorlesungen über Electricität und Magnetismus|volume=|publisher=Benedictus Gotthelf Teubner|location=Leipzig|year=1891|language=de|url=https://gutenberg.beic.it/webclient/DeliveryManager?pid=11946679}}
* {{Cite book|title=Vorlesungen über Electricität und Magnetismus|volume=|publisher=Benedictus Gotthelf Teubner|location=Leipzig|year=1891|language=de|url=https://gutenberg.beic.it/webclient/DeliveryManager?pid=11946679}}
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*{{cite journal |doi=10.1007/BF01558883 |title=Zur Erinnerung an Gustav Kirchhoff |date=1925 |last1=Warburg |first1=E. |journal=[[Die Naturwissenschaften]] |volume=13 |page=205 |bibcode = 1925NW.....13..205W |issue=11 |s2cid=30039558 }}
*{{cite journal |doi=10.1007/BF01558883 |title=Zur Erinnerung an Gustav Kirchhoff |date=1925 |last1=Warburg |first1=E. |journal=[[Die Naturwissenschaften]] |volume=13 |page=205 |bibcode = 1925NW.....13..205W |issue=11 |s2cid=30039558 }}
*{{cite journal |doi=10.1007/BF00625887 |title=Gustav Robert Kirchhoff (on the ninetieth anniversary of his death) |date=1977 |last1=Stepanov |first1=B. I. |journal=Journal of Applied Spectroscopy |volume=27 |page=1099 |bibcode=1977JApSp..27.1099S |issue=3 |s2cid=95181496 }}
*{{cite journal |doi=10.1007/BF00625887 |title=Gustav Robert Kirchhoff (on the ninetieth anniversary of his death) |date=1977 |last1=Stepanov |first1=B. I. |journal=Journal of Applied Spectroscopy |volume=27 |page=1099 |bibcode=1977JApSp..27.1099S |issue=3 |s2cid=95181496 }}
*{{cite journal |doi=10.1088/0031-9120/4/6/304 |title=Kirchhoff-Gustav Robert 1824–1887 |date=1969 |last1=Everest |first1=A. S. |journal=[[Physics Education]] |volume=4 |page=341 |bibcode=1969PhyEd...4..341E |issue=6 |s2cid=250765281 }}
*{{cite journal |doi=10.1088/0031-9120/4/6/304 |title=Kirchhoff-Gustav Robert 1824–1887 |date=1969 |last1=Everest |first1=A. S. |journal=[[Physics Education]] |volume=4 |page=341 |bibcode=1969PhyEd...4..341E |issue=6 |article-number=304 |s2cid=250765281 }}
*{{cite journal |first=Gustav |last=Kirchhoff |title=Ueber die Fraunhoferschen Linien |journal=[[Monatsberichte der Königliche Preussische Akademie der Wissenschaften zu Berlin]] |date=1860 |pages=662–665 |url=https://books.google.com/books?id=XDIXZiXWIuEC&pg=PA3 |isbn=978-1-113-39933-5 }} [http://hdl.handle.net/2027/mdp.39015050939274 HathiTrust full text]. Partial English translation available in [[Magie, William Francis]], ''A Source Book in Physics'' (1963). Cambridge: [[Harvard University Press]]. p.&nbsp;354-360.
*{{cite journal |first=Gustav |last=Kirchhoff |title=Ueber die Fraunhoferschen Linien |journal=[[Monatsberichte der Königliche Preussische Akademie der Wissenschaften zu Berlin]] |date=1860 |pages=662–665 |url=https://books.google.com/books?id=XDIXZiXWIuEC&pg=PA3 |isbn=978-1-113-39933-5 }} [http://hdl.handle.net/2027/mdp.39015050939274 HathiTrust full text]. Partial English translation available in [[Magie, William Francis]], ''A Source Book in Physics'' (1963). Cambridge: [[Harvard University Press]]. p.&nbsp;354-360.
*Kirchhoff, Gustav (1860). “IV. Ueber das Verhältniß zwischen dem Emissionsvermögen und dem Absorptionsvermögen der Körper für Wärme und Licht,” Annalen der Physik 185(2), 275–301. (coinage of term “blackbody”) [On the relationship between the emissivity and the absorptivity of bodies for heat and light]
*Kirchhoff, Gustav (1860). “IV. Ueber das Verhältniß zwischen dem Emissionsvermögen und dem Absorptionsvermögen der Körper für Wärme und Licht,” ''Annalen der Physik'' 185(2), 275–301. (coinage of term “blackbody”) [On the relationship between the emissivity and the absorptivity of bodies for heat and light]


== Further reading ==
== Further reading ==

Latest revision as of 16:38, 19 November 2025

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Gustav Robert Kirchhoff (Script error: No such module "IPA".; 12 March 1824 – 17 October 1887) was a German physicist and mathematician who contributed to the fundamental understanding of electrical circuits, spectroscopy, and the emission of black-body radiation by heated objects.[1][2] He coined the term black body in 1860.[3]

Several different sets of concepts are named "Kirchhoff's laws" after him, which include Kirchhoff's circuit laws, Kirchhoff's law of thermal radiation, Kirchhoff's diffraction formula, and Kirchhoff's law of thermochemistry.

The Bunsen–Kirchhoff Award for spectroscopy is named after Kirchhoff and his colleague, Robert Bunsen.

Biography

Gustav Robert Kirchhoff was born on 12 March 1824 in Königsberg, Prussia, the son of Friedrich Kirchhoff, a lawyer, and Johanna Henriette Wittke.[4] His family were Lutherans in the Evangelical Church of Prussia.

Kirchhoff studied at the University of Königsberg, where he attended the mathematico-physical seminar directed by C. G. J. Jacobi,[5] Franz Ernst Neumann, and Friedrich Julius Richelot. In 1845, while a student, Kirchhoff formulated two circuit laws—which are now ubiquitous in electrical engineering. He completed this study as a seminar exercise; it later became his doctoral thesis, supervised by Neumann.

In 1847, Kirchhoff graduated from the University of Königsberg and became a Privatdozent (unsalaried lecturer) at the University of Berlin, where he stayed until 1850 when he was offered a professorship at the University of Breslau. In 1854, he was called to the University of Heidelberg, where he collaborated with Robert Bunsen in spectroscopic work. In 1875, Kirchhoff returned to Berlin, where he remained until his death in 1887.

In 1857, Kirchhoff married Clara Richelot, the daughter of his mathematics professor Richelot; the couple had five children. In 1872, after Clara's death in 1869, he married Luise Brömmel.[6]

In 1864, Kirchhoff was elected a Member of the American Philosophical Society.[7] In 1884, he became a Foreign Member of the Royal Netherlands Academy of Arts and Sciences.[8]

Kirchhoff died on 17 October 1887 in Berlin at the age of 63. He is buried at Alter St.-Matthäus-Kirchhof (Old St. Matthew's Cemetery) in Schöneberg, Berlin (just a few meters from the graves of the Brothers Grimm).

Research

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Kirchhoff (left) and Robert Bunsen, Template:Circa

In 1857, Kirchhoff calculated that an electric signal in a resistanceless wire travels along the wire at the speed of light.[9][10]

In 1859, Kirchhoff proposed a law of thermal radiation, and gave a proof in 1861.

Together, Kirchhoff and Bunsen improved on Joseph von Fraunhofer's 1814 spectroscope, which Kirchhoff used to pioneer the identification of the elements in the Sun, showing in 1859 that the Sun contains sodium. Kirchhoff and Bunsen discovered caesium and rubidium in 1861.[11]

Kirchhoff contributed greatly to the field of spectroscopy by formalizing three laws that describe the spectral composition of light emitted by incandescent objects, building substantially on the discoveries of David Alter and Anders Jonas Ångström. In 1862, he was awarded the Rumford Medal "for his researches on the fixed lines of the solar spectrum, and on the inversion of the bright lines in the spectra of artificial light".Template:Efn

Kirchhoff also contributed to optics, carefully solving the wave equation to provide a solid foundation for Huygens' principle (and correct it in the process).[12][13]

Kirchhoff's circuit laws

Script error: No such module "Labelled list hatnote". Kirchhoff's first law states that at any node in an electrical circuit where current can branch, the sum of the currents leaving the node is equal to the sum of the currents entering the node. The second law states that the algebraic sum of the potential drops along a closed circuit, taken in any direction of flow, is equal to zero.[14]

Kirchhoff's three laws of spectroscopy

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File:Kirchhof laws.svg
Visual depiction of Kirchhoff's laws of spectroscopy
  1. A solid, liquid, or dense gas excited to emit light will radiate at all wavelengths and thus produce a continuous spectrum.
  2. A low-density gas excited to emit light will do so at specific wavelengths, and this produces an emission spectrum.
  3. If light composing a continuous spectrum passes through a cool, low-density gas, the result will be an absorption spectrum.

Kirchhoff did not know about the existence of energy levels in atoms. The existence of discrete spectral lines had been known since Fraunhofer discovered them in 1814. That the lines formed a discrete mathematical pattern was described by Johann Balmer in 1885. Joseph Larmor explained the splitting of the spectral lines in a magnetic field known as the Zeeman Effect by the oscillation of electrons.[15][16] These discrete spectral lines were not explained as electron transitions until the Bohr model of the atom in 1913, which helped lead to quantum mechanics.

Kirchhoff's law of thermal radiation

It was Kirchhoff's law of thermal radiation in which he proposed an unknown universal law for radiation that led Max Planck to the discovery of the quantum of action leading to quantum mechanics.

Kirchhoff's law of thermochemistry

Script error: No such module "Labelled list hatnote". Kirchhoff showed in 1858 that, in thermochemistry, the variation of the heat of a chemical reaction is given by the difference in heat capacity between products and reactants:

(∂ΔH∂T)p=ΔCp.

Integration of this equation permits the evaluation of the heat of reaction at one temperature from measurements at another temperature.[17][18]

Kirchhoff's theorem in graph theory

Kirchhoff also worked in the mathematical field of graph theory, in which he proved Kirchhoff's matrix tree theorem.

Works

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  • Vorlesungen über mathematische Physik. 4 vols., B. G. Teubner, Leipzig 1876–1894.
    • Vol. 1: Mechanik. 1. Auflage, B. G. Teubner, Leipzig 1876 (online).
    • Vol. 2: Mathematische Optik. B. G. Teubner, Leipzig 1891 (Herausgegeben von Kurt Hensel, online).
    • Vol. 3: Electricität und Magnetismus. B. G. Teubner, Leipzig 1891 (Herausgegeben von Max Planck, online).
    • Vol. 4: Theorie der Wärme. B. G. Teubner, Leipzig 1894, Herausgegeben von Max Planck[19]

See also

Notes

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References

Template:Reflist

Bibliography

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  • Script error: No such module "Citation/CS1". HathiTrust full text. Partial English translation available in Magie, William Francis, A Source Book in Physics (1963). Cambridge: Harvard University Press. p. 354-360.
  • Kirchhoff, Gustav (1860). “IV. Ueber das Verhältniß zwischen dem Emissionsvermögen und dem Absorptionsvermögen der Körper für Wärme und Licht,” Annalen der Physik 185(2), 275–301. (coinage of term “blackbody”) [On the relationship between the emissivity and the absorptivity of bodies for heat and light]

Further reading

External links

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  1. ↑ Script error: No such module "Citation/CS1".
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  12. ↑ Baker, Bevan B.; and Copson, Edward T.; The Mathematical Theory of Huygens' Principle, Oxford University Press, 1939, pp.Template:Nnbsp36–38.
  13. ↑ Miller, David A. B.; "Huygens's wave propagation principle corrected", Optics Letters 16, 1370–1372, 1991
  14. ↑ Corso di Fisicia 2 author Paul A .Tipler
  15. ↑ Buchwald, Jed Z.; and Warwick, Andrew; editors; Histories of the Electron: The Birth of Microphysics
  16. ↑ Script error: No such module "citation/CS1".
  17. ↑ Laidler, Keith J.; and Meiser, J. H.; "Physical Chemistry", Benjamin/Cummings 1982, p. 62
  18. ↑ Atkins, Peter; and de Paula, J.; "Atkins' Physical Chemistry", W. H. Freeman, 2006 (8th edition), p. 56
  19. ↑ Script error: No such module "Citation/CS1".
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