Biot, Jean-Baptiste 1774 - 1862

Jean-Baptiste Biot was born on 21 April 1774 in Paris. He was educated at the École Polytechnique before being appointed professor of mathematics at the University of Beauvais in 1797. He then became professor of mathematical physics at the Collège de France in 1800, and was elected a member of the French Academy of Sciences in 1803.

Biot accompanied Joseph-Louis Gay-Lussac on the first balloon flight undertaken for scientific purposes in 1804. The men showed that the Earth’s magnetic field does not vary noticeably with altitude, and they tested upper atmospheric composition.

In 1820 he and the physicist Félix Savart discovered that the intensity of the magnetic field set up by a current flowing through a wire is inversely proportional to the distance from the wire. This relationship is now known as the Biot-Savart law and is a fundamental part of modern electromagnetic theory. In 1835, while studying polarized light, Biot found that sugar solutions, among others, rotate the plane of polarization when a polarized light beam passes through. Further research revealed that the angle of rotation is a direct measure of the concentration of the solution. This fact became important in chemical analysis because it provided a simple, nondestructive way of determining sugar concentration. For this work Biot was awarded the Rumford Medal of the Royal Society in 1840.

Among his many writings, the most important work was 'Elementary Treatise on Physical Astronomy', published in 1805. He was made a member of the French Academy in 1856 and died in Paris on 3 February 1862.