André-Marie Ampère (1775-1836) was a physicist, mathematician and natural philosopher of French origin. He is known for his contributions to electrodynamics, the science that he founded and named, today known as electromagnetism..
Some refer to him as 'the Newton of electricity', a nickname given to him by the Scottish scientist James Clerk Maxwell in one of his treatises. Among his great contributions is the formulation of Ampère's law, in which he mathematically describes the relationship of the static magnetic field with the cause of origin.
It is also recognized for the invention of the astatic needle, an instrument that extraordinarily reduced the effect of terrestrial magnetism and that would allow the later development of the modern galvanometer. He also defined the unit to measure the electric current that bears his name, the ampere (A), as well as the instrument to measure it, the ammeter.
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André-Marie Ampère was born in Polémieux, near Lyon, on January 22, 1775. His parents were Jeanne-Antoinette Desutieres-Sarcey and Jean-Jacques Ampère, a successful silk merchant who formed a prosperous bourgeois family during the height of the French illustration.
His father was an admirer of the philosophy of Jean-Jacques Rousseau, who argued that children should avoid 'formal schooling' and have a more direct education with nature. This was the foundation of the education of Ampère, who reveled in the masterpieces of the French Enlightenment that lay in his father's stocked library..
From his childhood he showed signs of being a child prodigy, since long before he knew the figures, he calculated arithmetic sums using pebbles and cookie crumbs. It is also said that he tried to establish the protolanguage from which all human languages derive, inspired by the biblical story of the Tower of Babel..
For a few years his father began to teach him Latin, a language whose study he would return to later. Handling Latin would be useful to address the works of the physicists and mathematicians Leonhard Euler and Daniel Bernoulli.
When Lyon was taken over by the Army of the Convention in 1793, Ampère's father, who had been appointed justice of the peace by the revolutionary government, was imprisoned and guillotined as part of the Jacobin purges of the period..
Ampère was 18 years old. This event had a great impact on the life of the young man, who was isolated for more than a year in the family country house, with severe depression.
In 1796, he met Julie Carron, who would be his wife two years later. The death of his wife in 1804 was another severe blow that Ampère had to overcome. In 1806 he remarried, but legally separated two years later, receiving custody of his only son..
Around the year 1796 Ampère gave private classes in Lyon in mathematics, chemistry and languages. In 1801 he moved to Bourg, after being appointed professor of physics and chemistry at the École Centrale in Bourg-en-Bresse..
For the following year, Ampere published his first article on mathematical probability, in which he demonstrates how a player's chances increase with his wealth. This treatise was sent to the Paris Academy of Sciences in 1803.
In 1804, the same year that his wife died, Ampère returned to Lyon to take up the post of professor of mathematics at the lycée and, in parallel, a subordinate post at the Paris Polytechnic. By 1809 he had already been appointed professor of mathematics at that institution.
During the following years he developed various scientific investigations and wrote articles on mathematics, philosophy, chemistry and astronomy. In 1814, Ampère was invited to join the class of mathematicians at the new Institut National des Sciences.
He also offered courses in philosophy and astronomy at the University of Paris between 1819 and 1820. Four years later he managed to occupy the prestigious chair of experimental physics at the Collège de France..
In September 1820, during a demonstration by his friend François Arago at the Academy of Sciences, he learned of Hans Christian Ørsted's discovery. The Danish physicist had described how a magnetic needle acted on an adjacent electrical current.
Ampère devoted himself to studying the phenomenon and just a week later he presented an article in which he explained it in more detail. He managed to show how two parallel cables repel or attract each other, depending on the direction of the currents.
He also developed the astatic needle, which allowed him to measure the current that passed through that electrical circuit. Its purpose was to develop a mathematical and physical theory to understand the relationship between electricity and magnetism. During his research, he formulated what would later become known as Ampère's Law.
In 1827, Ampère published his magnum opus, Memory on the mathematical theory of electrodynamic phenomena, only deduced from experience. This was considered the founding treatise on electrodynamics, since it also coined the term of this new science. The text was a compendium of his studies during the last 7 years. For some it also marked the end of their original scientific work..
In subsequent years he devoted himself to studying all fields of knowledge, without dedicating himself exclusively to any as he had done before, but his work was not as forceful as his mathematical and experimental investigations in electricity had been..
While conducting a university inspection in Marseille, André-Marie Ampère died on June 10, 1836 at the age of 81. His remains rest in the Montmartre cemetery in Paris, France. His death occurred decades before electrodynamics was declared the cornerstone of the modern science of electromagnetism..
The great contributions of Ampère begin with the extension of the experimental work of Hans Christian Ørsted. He succeeded in showing that two parallel cable conductors carrying currents in the same direction have an attractive force for each other. On the contrary, if the current goes in reversed directions they repel each other.
Applying mathematics to generalize the physical laws of these experiments, he managed to formulate Ampère's law. This principle states that the mutual action of two sections of cable that carries current is proportional to its length and the intensity of its currents. Also check the harmony of this principle with the law of magnetic action, formulated by the French physicist Charles Augustin de Coulomb.
In his treatises he offered an understanding of the electromagnetic relationship and stated that 'magnetism was electricity in motion. ' He raised the existence of an 'electrodynamic molecule', a small current at the molecular level that is considered a precursor of the idea of the electron.
The result of this surface current, the now known amperian current, is similar to the real current flowing through a solenoid. Using this physical understanding of electromagnetic motion, Ampère managed to describe electromagnetic phenomena in such a way that they were empirically demonstrable and mathematically predictive..
For his experiments, Àmpere developed the astatic needle, which could be used to measure the intensity and direction of current passing through an electrical circuit. This is considered a kind of primitive galvanometer, as it would allow the later development of the instrument that is known today..
Another of his contributions was the determination of the basic unit of electric current that later received his name, the ampere, and the instrument to measure it the ammeter.
Among the works developed by Ampère is the treatise Considerations sur la théorie mathématique de jeu (1802), Mémoire sur la théorie mathématique des phénomènes électrodynamiques uniquement déduite de l'experience (1827) and his posthumous work Essai sur la philosophie des sciences. In addition, from a series of scientific papers and memoirs, he wrote two treatises on the integration of partial differential equations.
In life, Ampère was recognized by his contemporaries when he was appointed to prominent positions such as, for example, that of inspector general of the newly founded French Imperial University in 1808. He was also a member of the Academy of Sciences in Paris in 1814, as well as of various European academies in later years.
In 1881 an international convention established the ampere as the standard unit of electrical measurement, in recognition of the contribution of this French physicist in the creation of electrical science. In that same treaty, the coulomb, the volt, the ohm and the watt were established, in honor of the scientists who also made great contributions in the area..
André-Marie Ampère is one of the 72 illustrious French scientists and engineers, whose names appear on the four arches of the Eiffel Tower, along with those of Foucault, Fourier, Fresnel, Lavoisier, Malus or Poisson, among others..
He has also received multiple tributes such as the Ampère Prize awarded every year by the Academy of Sciences, a postage stamp issued in France in 1936, a street with his surname in Paris and another with his full name in Montpellier.
Numerous educational institutes are named after him in Arles, Lyon, Oyonnax, as well as the Lyon preparatory and primary schools in Paris, Grenoble, Saint-Germain-en-Laye, Nantes, Strasbourg, Oullins, Lille, Yzeure, Saint-Étienne du Rouvray, Caluire et Cuire. In addition, in Lyon, a square and the metro station with the most connections bear his name.
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