Ampère, André-Marie

Ampère, André-Marie

▪ French physicist
born Jan. 22, 1775, Lyon, France
died June 10, 1836, Marseille
 French physicist who founded and named the science of electrodynamics, now known as electromagnetism. His name endures in everyday life in the ampere, the unit for measuring electric current.

Early life
      Ampère, who was born into a prosperous bourgeois family during the height of the French Enlightenment, personified the scientific culture of his day. His father, Jean-Jacques Ampère, was a successful merchant, and also an admirer of the philosophy of Jean-Jacques Rousseau (Rousseau, Jean-Jacques), whose theories of education, as outlined in his treatise Émile, were the basis of Ampère's education. Rousseau argued that young boys should avoid formal schooling and pursue instead an “education direct from nature.” Ampère's father actualized this ideal by allowing his son to educate himself within the walls of his well-stocked library. French Enlightenment masterpieces such as Georges-Louis Leclerc, comte de Buffon (Buffon, Georges-Louis Leclerc, count de)'s Histoire naturelle, générale et particulière (begun in 1749) and Denis Diderot (Diderot, Denis) and Jean Le Rond d'Alembert (Alembert, Jean Le Rond d')'s Encyclopédie (volumes added between 1751 and 1772) thus became Ampère's schoolmasters. In addition, he used his access to the latest mathematical books to begin teaching himself advanced mathematics at age 12. His mother was a devout woman, so Ampère was also initiated into the Catholic faith along with Enlightenment science. The French Revolution (1787–99) that erupted during his youth was also formative. Ampère's father was called into public service by the new revolutionary government, becoming a justice of the peace in a small town near Lyon. Yet when the Jacobin (Jacobin Club) faction seized control of the Revolutionary government in 1792, Jean-Jacques Ampère resisted the new political tides, and he was guillotined on Nov. 24, 1793, as part of the Jacobin purges of the period.

      While the French Revolution brought these personal traumas, it also created new institutions of science that ultimately became central to André-Marie Ampère's professional success. He took his first regular job in 1799 as a modestly paid mathematics teacher, which gave him the financial security to marry and father his first child, Jean-Jacques, the next year. (Jean-Jacques Ampère (Ampère, Jean-Jacques) eventually achieved his own fame as a scholar of languages.) Ampère's maturation corresponded with the transition to the Napoleonic (Napoleon I) regime in France, and the young father and teacher found new opportunities for success within the technocratic structures favoured by the new French emperor.

      In 1802 Ampère was appointed a professor of physics and chemistry at the École Centrale in Bourg-en-Bresse. He used his time in Bourg to research mathematics, producing Considérations sur la théorie mathématique de jeu (1802; “Considerations on the Mathematical Theory of Games”), a treatise on mathematical probability that he sent to the Paris Academy of Sciences (Sciences, Academy of) in 1803. After the death of his wife in July 1803, Ampère moved to Paris, where he assumed a tutoring post at the new École Polytechnique in 1804. Despite his lack of formal qualifications, Ampère was appointed a professor of mathematics at the school in 1809. In addition to holding positions at this school until 1828, in 1819 and 1820 Ampère offered courses in philosophy and astronomy, respectively, at the University of Paris (Paris I–XIII, Universities of), and in 1824 he was elected to the prestigious chair in experimental physics at the Collège de France (France, Collège de). In 1814 Ampère was invited to join the class of mathematicians in the new Institut Impériale, the umbrella under which the reformed state Academy of Sciences would sit.

      Ampère engaged in a diverse array of scientific inquiries during these years leading up to his election to the academy—writing papers and engaging in topics ranging from mathematics and philosophy to chemistry and astronomy. Such breadth was customary among the leading scientific intellectuals of the day.

Founding of electromagnetism
      Had Ampère died before 1820, his name and work would likely have been forgotten. In that year, however, Ampère's friend and eventual eulogist François Arago (Arago, François) demonstrated before the members of the French Academy of Sciences (Sciences, Academy of) the surprising discovery of Danish physicist Hans Christiaan Ørsted (Ørsted, Hans Christian) that a magnetic needle is deflected by an adjacent electric current. Ampère was well prepared to throw himself fully into this new line of research.

      Ampère immediately set to work developing a mathematical and physical theory to understand the relationship between electricity and magnetism. Extending Ørsted's experimental work, Ampère showed that two parallel wires carrying electric currents repel or attract each other, depending on whether the currents flow in the same or opposite directions, respectively. He also applied mathematics in generalizing physical laws from these experimental results. Most important was the principle that came to be called Ampère's law, which states that the mutual action of two lengths of current-carrying wire is proportional to their lengths and to the intensities of their currents. Ampère also applied this same principle to magnetism, showing the harmony between his law and French physicist Charles Augustin de Coulomb (Coulomb, Charles-Augustin de)'s law of magnetic action. Ampère's devotion to, and skill with, experimental techniques anchored his science within the emerging fields of experimental physics.

      Ampère also offered a physical understanding of the electromagnetic relationship, theorizing the existence of an “electrodynamic molecule” (the forerunner of the idea of the electron) that served as the constituent element of electricity and magnetism. Using this physical understanding of electromagnetic motion, Ampère developed a physical account of electromagnetic phenomena that was both empirically demonstrable and mathematically predictive. In 1827 Ampère published his magnum opus, Mémoire sur la théorie mathématique des phénomènes électrodynamiques uniquement déduite de l'experience (Memoir on the Mathematical Theory of Electrodynamic Phenomena, Uniquely Deduced from Experience), the work that coined the name of his new science, electrodynamics, and became known ever after as its founding treatise. In recognition of his contribution to the making of modern electrical science, an international convention signed in 1881 established the ampere as a standard unit of electrical measurement, along with the coulomb, volt, ohm, and watt, which are named, respectively, after Ampère's contemporaries Coulomb, Alessandro Volta (Volta, Conte Alessandro) of Italy, Georg Ohm (Ohm, Georg Simon) of Germany, and James Watt (Watt, James) of Scotland.

      The 1827 publication of Ampère's synoptic Mémoire brought to a close his feverish work over the previous seven years on the new science of electrodynamics. The text also marked the end of his original scientific work. His health began to fail, and he died while performing a university inspection, decades before his new science was canonized as the foundation stone for the modern science of electromagnetism.

J.B. Shank

Additional Reading
James R. Hofmann, André-Marie Ampère: Enlightenment and Electrodynamics (1995), is the definitive biography in the English language.

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Universalium. 2010.

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  • Ampère, André-Marie — (1775 1836)    scientist, mathematician    Born near lyon, the son of a city official, André Marie Ampère became interested in mathematics at an early age. He is best known for his important contributions to the study of electrodynamics, the… …   France. A reference guide from Renaissance to the Present

  • Ampère , André Marie — (1775–1836) French physicist and mathematician Ampère was born in Lyons, France, where his father was a wealthy merchant. He was privately tutored, and to a large extent self taught. His genius was evident at an early age. He was particularly… …   Scientists

  • Ampère, André Marie — born Jan. 22, 1775, Lyon, France died June 10, 1836, Marseille French physicist, founder of the science of electromagnetism. A prodigy who mastered the entire known field of mathematics by age 12, he became a professor of physics, chemistry, and… …   Universalium

  • Ampère, André Marie — (22 ene. 1775, Lyon, Francia–10 jun. 1836, Marsella). Físico francés, fundador de la ciencia del electromagnetismo. Niño prodigio, a los 12 años de edad ya dominaba todo el campo conocido de la matemática. Fue profesor de física, química y… …   Enciclopedia Universal

  • Ampère, André Marie —  (1775–1836) French physicist. The unit of electricity named after him is ampere (no cap., no accent) …   Bryson’s dictionary for writers and editors

  • Ampère, André-Marie — ► (1775 1836) Físico y matemático francés. Fue profesor en la Escuela Politécnica de París En 1802 publicó un estudio científico sobre la teoría del juego. Descubrió las leyes que rigen la desviación producida en una aguja magnética por una… …   Enciclopedia Universal

  • AMPÈRE`, ANDRÉ MARIE —    a French mathematician and physicist, born at Lyons; distinguished for his discoveries in electro dynamics and magnetism, and the influence of these on electro telegraphy and the general extension of science (1775 1836) …   The Nuttall Encyclopaedia

  • André-Marie Ampère — (* 20. Januar 1775 in Lyon, Frankreich; † 10. Juni 1836 in Marseille) war ein französischer Physiker und Mathematiker. Nach ihm ist die internationale Einheit der Stromstärke Ampere benannt …   Deutsch Wikipedia

  • Andre-Marie Ampere — André Marie Ampère Pour les articles homonymes, voir Ampère. André Marie Ampère André Marie Ampère, né à Lyon le 20 …   Wikipédia en Français

  • André Marie Ampère — Pour les articles homonymes, voir Ampère. André Marie Ampère André Marie Ampère, né à Lyon le 20 …   Wikipédia en Français

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