Michael Faraday
1791 - 1867
 

The English physicist and chemist Michael Faraday discovered benzene and the principles of current induction.

One of a blacksmith's 10 children, Michael Faraday was born on Sept. 22, 1791, in Newington, Surrey. The family soon moved to London, where young Michael picked up the rudiments of reading, writing, and arithmetic. At the age of 14 he was apprenticed to a bookbinder and bookseller. He read ravenously and attended public lectures, including some by Sir Humphry Davy.

Faraday's career began when Davy, temporarily blinded in a laboratory accident, appointed Faraday as his assistant at the Royal Institution. With Davy as a teacher in analytical chemistry, Faraday advanced in his scientific apprenticeship and began independent chemical studies. By 1825 he discovered benzene and had become the first to describe compounds of chlorine and carbon. He adopted the atomic theory to explain that chemical qualities were the result of attraction and repulsion between united atoms. This proved to be the theoretical foundation for much of his future work.

Faraday had already done some work in magnetism and electricity, and it was in this field that he made his most outstanding contributions. His first triumph came when he found a solution to the problem of producing continuous rotation by use of electric current, thus making electric motors possible. Hans Oersted had discovered the magnetic effect of a current, but Faraday grasped the fact that a conductor at rest and a steady magnetic field do not interact and that to get an induced current either the conductor or the field has to move. On Aug. 29, 1831, he discovered electromagnetic induction.

During the next 10 years Faraday explored and expanded the field of electricity. In 1834 he announced his famous two laws of electrolysis. Briefly, they state that for any given amount of electrical force in an electrochemical cell, chemical substances are released at the electrodes in the ratio of their chemical equivalents. He also invented the voltameter, a device for measuring electrical charges, which was the first step toward the later standardization of electrical quantities.

Faraday continued to work in his laboratory, but his health began to deteriorate and he had to stop work entirely in 1841. Almost miraculously, however, his health improved and he resumed work in 1844. He began a search for an interaction between magnetism and light and in 1845 turned his attention from electrostatics to electromagnetism. He discovered that an intense magnetic field can rotate the plane of polarized light, a phenomenon known today as the Faraday effect. In conjunction with these experiments he showed that the magnetic line of force is conducted by all matter. Those which were good conductors he called paramagnetics, while those which conducted the force poorly he named diamagnetics. Thus, the energy of a magnet is in the space around it, not in the magnet itself. This is the fundamental idea of the field theory.

Faraday was a brilliant lecturer, and through his public lectures he did a great deal to popularize science. Shortly after he became head of the Royal Institution in 1825, he inaugurated the custom of giving a series of lectures for young people during the Christmas season. This tradition has been maintained, and over the years the series have frequently been the basis for fascinating, simply written, and informative books.

On Aug. 25, 1867, Faraday died in London.

The admiration of physicists for Faraday has been demonstrated by naming the unit of capacitance the farad and a unit of charge, the faraday. No other man has been doubly honoured in this way. His name also appears frequently in connection with effects, laws, and apparatus. These honours are proper tribute to the man who was possibly the greatest experimentalist who ever lived.
 

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Michael Faraday was one of the greatest scientists of the 19th century. His early life closely paralleled that of Benjamin Franklin. Both were part of a large family; both were apprenticed in the printing trade; both read voraciously and became self-educated; and both loved science.

Faraday was born in Newington, Surrey, England, on September 22, 1791. His father, a blacksmith, could not afford a formal education for Michael, and so the boy received just the bare essentials and was apprenticed to a bookbinder. In some ways this apprenticeship was a stroke of good fortune for Michael because it gave him the opportunity to read all that he desired. He studied the articles about electricity in the Encyclopaedia Britannica, read a chemistry textbook, and was very interested in magnetism. In 1812 Faraday obtained tickets to attend the lectures of Humphry Davy at the Royal Institution. Faraday took 386 pages of notes and had them bound in leather and sent to Sir Joseph Banks (1743-1820), who was president of the Royal Society of London, with the hope of making a favorable impression. Unfortunately, Banks never responded. No matter--Faraday then sent a copy directly to Davy along with a job application to be Davy's assistant. Davy was very impressed, but he already had an assistant. However, shortly thereafter, Davy fired his assistant for brawling, contacted Faraday, and offered him the job of "washing bottles." This was not exactly what Faraday had in mind, but it was a step in the right direction and he accepted.

In 1813 Davy resigned his post at the Royal Institution, married a wealthy widow, and began an extended trip through Europe. The trip afforded Faraday the opportunity to meet such famous men as Italian physicist Alessandro Volta and French chemist Louis-Nicolas Vauquelin (1763-1829). In 1820, Danish physicist Hans Christian Oersted (1777-1851) had discovered that an electric current produced a magnetic field. This had set off a flurry of investigation by other scientists, among them Faraday, who was now back in England. Within a year of Oersted's discovery, Faraday had built a device which essentially consisted of a hinged wire, a magnet and a chemical battery. When the current was turned on, a magnetic field was set up in the wire, and it began to spin around the magnet. Faraday had just invented the electric motor.

Faraday's motor was certainly an interesting device, but it was treated as a toy. But Faraday had a greater goal in sight. Oersted had converted electric current into a magnetic force; Faraday intended to reverse the process and create electricity from magnetism. Taking an iron ring, Faraday wrapped half of it with a coil of wire that was attached to a battery and switch. André Marie Ampère (1775-1836) had shown that electricity would set up a magnetic field in the coil. The other half of the ring was wrapped with a wire that led to a galvanometer. In theory, the first coil would set up a magnetic field that the second coil would intercept and convert back to electric current which the galvanometer would register. Faraday threw the switch and received instant gratification: the experiment worked, a device that became known as the transformer. However, the result was not exactly what he expected. Instead of registering a continuous current, the galvanometer moved only when the circuit was opened or closed. Ampère had observed the same effect a decade earlier but ignored it because it did not fit his theories. Deciding to make the theory fit the observation, instead of the other way around, Faraday concluded that when the current was turned on or off, it caused magnetic" lines of force" from the first coil to expand or contract across the second coil, inducing a momentary flow of current in the second coil. In this way Faraday discovered the principle of electrical induction.

Meanwhile, in the United States, physicist Joseph Henry had independently made the same discovery. Faraday's affiliation with Davy had been suffering because Davy was extremely jealous of his former assistant, who was now eclipsing him. The situation escalated following Faraday's invention of the transformer; Davy claimed the idea for the experiment had been his. When Faraday was nominated to become a member of the Royal Society in 1824, Davy cast the only negative vote.

Having shown that magnetism could produce electricity, Faraday's next goal was to produce a continuous current instead of just a momentary spurt. This time he decided to reverse an experiment made by Dominique Arago (1786-1853). In1824 Arago had discovered that a rotating copper disk deflected a magnetic needle. This, explained Faraday, was an example of magnetic induction. Faraday planned to use a magnetic field to set up an electric current. In 1831 Faraday took a copper disk and spun it between the poles of a permanent magnet. This set up an electric current in the disk which could be passed through a wire and put to work. So long as the wheel spun, current was produced. This simple experiment produced the greatest electrical invention in history: the electric generator. It took five decades and other inventions to make generators practical, but Faraday had pointed the way.

Faraday is especially remembered for his use of intuition in his scientific discoveries, making minimal use of mathematics. Unfortunately, he suffered a mental breakdown in 1839 from which he never fully recovered, and he was forced to leave the laboratory work to others. In addition to his inventions, he had compiled a number of notable discoveries: "magnetic lines of force," the compound benzene, how to liquify various gasses, and the laws of electrolysis. He also developed the concept of a "field"--a force, like magnetism or electric fields or gravity, that extends throughout space and is produced by magnets or electric charge or, in the case of gravity, mass. James Clerk Maxwell later developed his famous equations describing electromagnetism using this concept, acknowledging his debt to Faraday.

On August 25, 1867, Faraday died at Hampton Court, Middlesex, England. His accomplishments were all the more remarkable considering he had had no formal training in science or mathematics, yet was able to establish the fundamental nature of electricity and magnetism.

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