A Gallery of Electromagnetic Personalities 3...

Ampère, Biot, Fresnel

André-Marie Ampère (1775-1836) was a child prodigy whose early life was marred by tragedy: Ampère's father was beheaded in his presence during the Revolution and, later, his wife died four years after their marriage. As a scientist, Ampère had flashes of inspiration which he would pursue to their conclusion. When he learned of Ørsted's discovery in 1820 that a magnetic needle is deflected by a varying nearby current, he prepared within a week the first of several papers on the theory of this phenomenon, formulating the law of electromagnetism (Ampère's law) that describes mathematically the magnetic force between two circuits.

Jean-Baptiste Biot (1774-1862) along with Félix Savart formulated the Biot-Savart law of magnetic fields. In 1804 he took part in the first balloon ascension for scientific research and showed that the terrestrial magnetic field does not vary appreciably with altitude.

Augustin-Jean Fresnel (1788-1827) was an engineer who lost his job after Napoleon returned from Elba in 1815. He became involved in optics and pioneered in establishing the wave theory of light. When he presented the wave theory, Poisson objected that the theory predicted a bright spot in the center of the shadow of a circular object. When this phenomenon was observed by Arago, objection to the wave theory collapsed. Photo: Fresnel lenses.

Gauss, Weber

Karl Friedrich Gauss (1777-1855) ranks as one of the greatest mathematicians of all time. At an early age he overturned the theories and methods of 18th-century mathematics. Beginning in 1830, Gauss worked closely with Weber. They organized a worldwide system of stations for systematic observations of terrestrial magnetism. The most important result of their work in electromagnetism was the development, by others, of telegraphy. (Gauss, however, was frightened at the thought of worldwide communication.) Gauss lived to an advanced age, and having systematically studied the financial markets and invested accordingly, he died a very wealthy man.

Wilhelm Eduard Weber (1804-1891), a German physicist, who with his friend Gauss investigated terrestrial magnetism, also established a system of absolute electrical units. He also often collaborated with his two brothers who were renowned physiologists. Weber was a professor of physics at Göttingen, but he was removed from his position for several years when he joined a group of professors who signed a protest against the ruler of Hanover who had revoked the liberal constitution. His work on the ratio between the electrodynamic and electrostatic units was crucial to Maxwell's electromagnetic theory of light. He was described in this way: "He speaks and stutters on unceasingly, one has nothing to do but listen."