Michael Faraday

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Michael Faraday

Michael Faraday (September 22, 1791 - August 25, 1867) was a British scientist (a physicist and chemist) who contributed to the fields of electromagnetism and electrochemistry and invented the Bunsen burner.

Michael Faraday was one of the great scientists in history. Some historians of science refer to him as the greatest experimentalist in the history of science. It was largely due to his efforts that electricity became a vital energy source.

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Early career

Michael Faraday was born in Newington, near present-day Elephant and Castle, London. His family was poor and he had to educate himself. At fourteen he became apprenticed to a book-binder and seller and during his seven year apprenticeship read many books, developing an interest in science.

At the age of twenty he attended lectures by the eminent scientist Humphry Davy, president of the Royal Society, and was interested. After he sent him 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. However, it was not long before Faraday surpassed Davy.

Scientific career

His greatest work was with electricity. In 1821, soon after the Danish chemist, Ørsted, discovered the phenomenon of electromagnetism, Davy and William Hyde Wollaston tried but failed to design an electric motor. Faraday, having discussed the problem with the two men, went on to build two devices to produce what he called electromagnetic rotation: a continuous circular motion from the circular magnetic force around a wire. A wire extending into a pool of mercury with a magnet placed inside would rotate around the magnet if charged with electricity by a chemical battery. These experiments and inventions form the foundation of modern electromagnetic technology. Unwisely, Faraday published his results without acknowledging his debt to Wollaston and Davy, and the resulting controversy caused Faraday to withdraw from electromagnetic research for several years.

Ten years later, in 1831, he began his great series of experiments in which he discovered electromagnetic induction. He found that if he moved a magnet through a loop of wire, an electric current passed through the wire. His demonstrations exposed the concept that electric current produced magnetism. Faraday then used the principle to construct the electric dynamo, the ancestor of modern power generators.

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 Faraday's law (later incorporated into Maxwell's equations) which has evolved into the generalization known as field theory.

Faraday also dabbled in chemistry, discovering chemical substances such as benzene, inventing the system of oxidation numbers, and liquefying gases. He also discovered the laws of electrolysis and popularized terminology such as anode, cathode, electrode, and ion.

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.

Miscellaneous

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.

Faraday was known for designing ingenious experiments, but lacked a good mathematics education. He was regarded as handsome and modest, declining a knighthood and presidency of the Royal Society (Davy's old position).

The unit of capacitance, the farad is named after him; his picture has been printed on British £20 banknotes.

Faraday had a wife but no children. His 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.

Quotations

"Nothing is too wonderful to be true."
"Work. Finish. Publish." - his well-known advice to the young William Crookes