André-Marie Ampère

Founder of electrodynamics who formulated Ampère's Law, laying the groundwork for modern electromagnetism and electrical engineering

André-Marie Ampère (1775–1836) revolutionized physics through his pioneering work in electromagnetism. His 1827 Memoir on the Mathematical Theory of Electrodynamic Phenomena established the theoretical foundation for understanding electric currents and magnetic fields. The SI unit of electric current—the ampere—bears his name, testifying to his enduring legacy.

Ampère's breakthrough came in 1820 when he demonstrated that parallel wires carrying currents attract or repel each other, quantifying this phenomenon in Ampère's Law. This discovery, building on Hans Christian Ørsted's observation of compass needle deflection, unified electricity and magnetism into the field of electrodynamics. His mathematical framework became crucial for developing technologies from electric motors to telecommunications.

Beyond physics, Ampère contributed to chemistry (discovering fluorine) and mathematics (advancing partial differential equations). Despite personal tragedies—including his father's execution during the French Revolution—he became a professor at Collège de France and member of the French Academy of Sciences. The Ampère Museum in Lyon preserves his scientific legacy.

Modern applications of Ampère's work include MRI machines, particle accelerators, and power grids. His 1820 invention of the astatic needle (precursor to the galvanometer) enabled precise current measurements. James Clerk Maxwell later described Ampère as the 'Newton of electricity' for establishing electromagnetic theory's mathematical basis.