Michael
FaradayMichael
Faraday (1791-1867)
was a British scientist who contributed to the field of electromagnetism and invented
the Bunsen burner. Michael
Faraday was born on September 22, 1791, near Elephant and Castle, London. At fourteen
he apprenticed as a book-binder and during his seven year apprenticeship developed
an interest in science. After
he sent Humphry Davy a sample of notes that he had made, Davy employed Faraday
as his assistant. In a class-ridden society, he was not considered to be a gentleman,
and it is said that Davy's wife refused to treat him as an equal and would not
associate with him socially. His
greatest work was with electricity. In 1821, soon after the Danish chemist, Ørsted,
discovered the phenomenon of electromagnetism, Faraday built two devices to produce
what he called electromagnetic rotation: that is a continuous circular motion
from the circular magnetic force around a wire. The electric generator used a
magnet to generate electricity. These experiments and inventions form the foundation
of modern electromagnetic technology. Ten
years later, in 1831, he began his great series of experiments in which he discovered
electromagnetic induction. His demonstrations exposed the concept that electric
current produced magnetism. Faraday proposed that electromagnetic forces extended
into the empty space around the conductor, but did not complete his work over
this proposal. Faraday's experimental visualization, of lines of flux emanating
from charged bodies, was mathematically modelled by James Clerk Maxwell,
which has evolved into the generalization known as field theory. In
1845 he discovered what is now called the Faraday effect and the phenomenon that
he named diamagnetism. The plane of polarization of linearly polarized light propagated
through a material medium can be rotated by the application of an external magnetic
field aligned in the propagation direction. He wrote in his notebook, "I have
at last succeeded in illuminating a magnetic curve or line of force
and in magnetising a ray of light". This established that magnetic force
and light were related. In
the work on static electricity, Faraday demonstrated that the charge only resided
on the exterior of a charged conductor, and exterior charge had no influence on
anything enclosed within a conductor; this shielding effect is used in what is
now known as a Faraday cage. He
gave a successful series of lectures on the chemistry and physics of flames at
the Royal Institution, entitled `The Natural History of a candle'; this
was the origin of the Christmas lectures for young people that are still given
there every year. The
unit of capacitance, the farad is named after him; his picture has been printed
on British £20 banknotes. Faraday's
sponsor and mentor was John 'Mad Jack' Fuller, who created the Fullerian Professorship
of Chemistry at the Royal Institution. Faraday was the first, and most famous,
holder of this position to which he was appointed for life. He
died at his house at Hampton Court on August 25, 1867.
- Faraday's Diary, ¶
7718, 30 Sept. 1845 and ¶ 7504, 13 Sept. 1845
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