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discoverer of electromagnetic induction
Michael Faraday was born in Newington, Surrey, England, on September 22, 1791, the son of a blacksmith. He received little formal education, but while apprenticed to a bookbinder in London he was able to read books on scientific subjects.
In 1812, Faraday attended a series of lectures given by the British chemist Sir Humphry Davy. Afterwards, he sent Davy a three hundred-page book, complete with illustrations, based on notes he had taken during the lectures, together with a request for employment. Davy was impressed, and Faraday was hired as his assistant in 1813.
Faraday was elected to the Royal Society in 1824, and was appointed director of the laboratory of the Royal Institution in 1825. In 1833 he succeeded Davy as Fullerian Professor of Chemistry at the Institution in 1833, a position he held for the rest of his life. In 1835 he was granted a pension of 300 pounds a year for life.
Faraday's earliest work was in the field of chemistry, primarily as an assistant to Davy. He made a special study of chlorine and discovered two new chlorides of carbon. He also made the first rough experiments on the diffusion of gases, succeeded in liquefying several gases, investigated the alloys of steel, and produced several new kinds of glass intended for optical purposes.
Faraday's experiments also led to his formulation of the second law of electrolysis -- when the same quantity of electricity is passed through several electrolytes, the mass of the substances deposited are proportional to their respective chemical equivalent or equivalent weight.
Research into Electricity and Magnetism
Faraday's real interest lay in the link between magnetism and electricity. He was convinced that magnetism could be made to generate electricity, just as electricity could create magnetism.
The first experiment with electricity which he recorded was the construction of a voltaic pile, with which he decomposed sulphate of magnesia.
In 1821, building on the work of Danish physicist Hans Christian Řersted, Faraday built two devices to produce what he called electromagnetic rotation -- a continuous circular motion from the circular magnetic force around a wire and a wire extending into a pool of mercury with a magnet placed inside would rotate around the magnet if supplied with current from a chemical battery. Although Faraday carried this line of research no further, he had succeeded in building the first rudimentary electric motor.
In 1831, in a series of historic experiments, Faraday discovered the phenomenon of electromagnetic induction -- the production of electricity by means of fluctuating magnetic intensities. The most famous of his experiments used a ring of soft iron wraped in two windings of insulated wire. The ends of one winding were connected to a galvanometer, which measures current. When the other wire was connected to a battery, nothing appeared to happen even though Faraday knew that the iron was temporarily magnetized by the current. When the circuit was completed or broken the galvanometer recorded a pulse of electricity. Faraday correctly assumed that while the intensity of the iron's magnetism was rising or falling, an induced current was produced. Faraday used his discovery to build the first dynamo, the model for the generators that today supply most of the world's electricity.
coil used by Faraday in his discovery of
Faraday's work led him to formulate the idea of "lines of force" to explain magnetism. He imagined magnetic force stretching out from the poles of a magnet in all directions, filling space with a kind of "field" of force. Lines could be drawn connecting all points where the strength of the force was equal, allowing the magnetic field to be mapped. His idea is now known as electromagnetic theory.
In 1845, Faraday discovered the phenemenon that he named diamagnetism, which established that magnetic force and light were related. This phenomenon is now called the Faraday Effect.
In his 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 with a conductor. This shielding effect is used in what is now known as a Faraday Cage.
Faraday published many of his theories and experimental results in the three-volume work Experimental Researches in Electricity (1839-1855).
Faraday died in Hampton Court, Surrey, England, on August 25, 1867.
The farad, a unit of electricity that measures capacitance, an amount of electrical charge, was named after Michael Faraday.
Anthony Feldman and Peter Ford. Scientists and Inventors, The People Who Made Technology from Earliest Times to Present Day. New York: Facts on File, 1979
Eric Weisstein's World of Scientific Biography scienceworld.wolfram.com
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