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André-Marie Ampère

1775 - 1836

André Marie Ampére, 1775 - 1836, French physicist

André-Marie Ampère, 1775 - 1836, was a French physicist and mathematician, who was a founder of the science of electrodynamics.

  • Nationality
  • French

  • Subject
  • Physics

  • Fields
  • electromagnetism, mathematics

  • Distinctions
  • The S.I. base unit for electric current, ampere, is named in his honour, as is the related ammeter.

  • Posts
  • École Polytechnique, professor of mathematics

    Chair in experimental physics at the collège de France, 1824

    Foreign Member of the Royal Society, 1827.

  • Publications
  • Considérations sur la théorie mathématique de jeu 1802 (Considerations on the Mathematical Theory of Games), concerning probability.

    Mémoire sur la théorie mathématique des phénomènes électrodynamiques uniquement déduite de l’experience, 1827 (Memoir on the Mathematical Theory of Electrodynamic Phenomena, Uniquely Deduced from Experience), which introduces the term electrodynamics.

  • Laws
  • Ampère's Law: the mutual action of two lengths of current-carrying wire is proportional to their lengths and the intensities of their currents.

  • Theories
  • One of the founders of classical electromagnetism

    Mathematical and physical theory explaining the relationship between electricity and magnetism.

    Ampère explained the phenomenon of electricity with the existence of an "electrodynamic molecule", which today is called the electron.

  • Equations
  • Ampère's Law:

    $$∮_C{B}⋅dl = ∫∫_S (μ_0J + μ_0ε_0{δ}/{δt}E) ⋅ dS$$

    where $B$ is the magnetic field strength around a closed surface $C$, $ε_0$ is the electric constant, J is the current density ($Am^{-2}$), and $E$ the electric field strength.

  • Experiments/Discoveries
  • Ampère extended Hans Christian Ørsted's magnetic effect from an electrical current to two parallel wires through which electric currents are travelling. The force between the two wires is the basis for the ampere unit.

    Ampère made considerable contributions to the emerging field of experimental physics.

The S.I. base unit for electric current is the ampere. Ampère's wrote laws and equations describing the phenomenon of magnetism and electricity, and their interaction.

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