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Michael Faraday
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Scientific achievements
Chemistry
Faraday's earliest chemical work was as an assistant to Humphry Davy. Faraday 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, a phenomenon first pointed out by John Dalton, the physical importance of which was more fully brought to light by Thomas Graham and Joseph Loschmidt. He succeeded in liquefying several gases; he investigated the alloys of steel, and produced several new kinds of glass intended for optical purposes. A specimen of one of these heavy glasses afterwards became historically important as the substance in which Faraday detected the rotation of the plane of polarisation of light when the glass was placed in a magnetic field, and also as the substance which was first repelled by the poles of the magnet.
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Timeline
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1791 Born
1824 After much controversy, Michael Faraday is finally elected as a member of the Royal Society with only one vote against.
1867 Died
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Encyclopedia
Scientific achievements
Chemistry
Faraday's earliest chemical work was as an assistant to Humphry Davy. Faraday 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, a phenomenon first pointed out by John Dalton, the physical importance of which was more fully brought to light by Thomas Graham and Joseph Loschmidt. He succeeded in liquefying several gases; he investigated the alloys of steel, and produced several new kinds of glass intended for optical purposes. A specimen of one of these heavy glasses afterwards became historically important as the substance in which Faraday detected the rotation of the plane of polarisation of light when the glass was placed in a magnetic field, and also as the substance which was first repelled by the poles of the magnet. He also endeavoured, with some success, to make the general methods of chemistry, as distinguished from its results, the subject of special study and of popular exposition.
He invented an early form of what was to become the Bunsen burner, which is used almost universally in science laboratories as a convenient source of heat.
Faraday worked extensively in the field of chemistry, discovering chemical substances such as benzene (which he called bicarburet of hydrogen), inventing the system of oxidation numbers, and liquefying gases such as chlorine. In 1820 Faraday reported on the first syntheses of compounds made from carbon and chlorine, C2Cl6 and C2Cl4, and published his results the following year. Faraday also determined the composition of the chlorine clathrate hydrate, which had been discovered by Humphry Davy in 1810.
Faraday also discovered the laws of electrolysis and popularised terminology such as anode, cathode, electrode, and ion, terms largely created by William Whewell.
Faraday was the first to report what later came to be called metallic nanoparticles. In 1847 he discovered that the optical properties of gold colloids differed from those of the corresponding bulk metal. This was probably the first reported observation of the effects of quantum size, and might be considered to be the birth of nanoscience.
Electricity and magnetism Faraday's greatest work was probably with electricity and magnetism. The first experiment which he recorded was the construction of a voltaic pile with seven halfpence pieces, stacked together with seven disks of sheet zinc, and six pieces of paper moistened with salt water. With this pile he decomposed sulphate of magnesia (first letter to Abbott, July 12, 1812).
In 1821, soon after the Danish physicist and chemist, Hans Christian Ørsted discovered the phenomenon of electromagnetism, Davy and British scientist 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 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. The latter device is known as a homopolar motor. These experiments and inventions form the foundation of modern electromagnetic technology. 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.
At this stage, there is also evidence to suggest that Davy may have been trying to slow Faraday’s rise as a scientist (or natural philosopher as it was known then). In 1825, for instance, Davy set him onto optical glass experiments, which progressed for six years with no great results. It was not until Davy's death, in 1829, that Faraday stopped these fruitless tasks and moved on to endeavors that were more worthwhile. Two years later, in 1831, he began his great series of experiments in which he discovered electromagnetic induction. Joseph Henry likely discovered self-induction a few months earlier and both may have been anticipated by the work of Francesco Zantedeschi in Italy in 1829 and 1830.
Faraday's breakthrough came when he wrapped two insulated coils of wire around an iron ring, and found that upon passing a current through one coil, a momentary current was induced in the other coil. This phenomenon is known as mutual induction. The iron ring-coil apparatus is still on display at the Royal Institution. In subsequent experiments he found that if he moved a magnet through a loop of wire, an electric current flowed in the wire. The current also flowed if the loop was moved over a stationary magnet. His demonstrations established that a changing magnetic field produces an electric field. This relation was mathematically modelled by Faraday's law, which subsequently became one of the four Maxwell equations. These in turn have evolved into the generalisation known today as field theory.
Faraday later used the principle to construct the electric dynamo, the ancestor of modern power generators.
In 1839 he completed a series of experiments aimed at investigating the fundamental nature of electricity. Faraday used "static", batteries, and "animal electricity" to produce the phenomena of electrostatic attraction, electrolysis, magnetism, etc. He concluded that, contrary to scientific opinion of the time, the divisions between the various "kinds" of electricity were illusory. Faraday instead proposed that only a single "electricity" exists, and the changing values of quantity and intensity (voltage and charge) would produce different groups of phenomena.
Near the end of his career Faraday proposed that electromagnetic forces extended into the empty space around the conductor. This idea was rejected by his fellow scientists, and Faraday did not live to see this idea eventually accepted. Faraday's concept of lines of flux emanating from charged bodies and magnets provided a way to visualise electric and magnetic fields. That mental model was crucial to the successful development of electromechanical devices which dominated engineering and industry for the remainder of the 19th century.
Diamagnetism
In 1845, Faraday discovered that many materials exhibit a weak repulsion from a magnetic field, a phenomenon he named diamagnetism.
Faraday also found that the plane of polarisation of linearly polarised light can be rotated by the application of an external magnetic field aligned in the direction the light is moving. This is now termed the Faraday effect. 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.
Late in life (1862), Faraday used a spectroscope to search for a different alteration of light, the change of spectral lines by an applied magnetic field. However, the equipment available to him was insufficient for a definite determination of a spectral change. Pieter Zeeman later used an improved apparatus to study the same phenomenon, publishing his results in 1897 and receiving the 1902 Nobel Prize in Physics for his success. In both his 1897 paper and his Nobel acceptance speech, Zeeman referred to Faraday's work.
Faraday cage
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 within a conductor. This is because the exterior charges redistribute such that the interior fields due to them cancel. This shielding effect is used in what is now known as a Faraday cage.
Faraday was an excellent experimentalist who conveyed his ideas in clear and simple language. However, his mathematical abilities did not extend as far as trigonometry or any but the simplest algebra. It was James Clerk Maxwell who took the work of Faraday, and others, and consolidated it with a set of equations that lie at the base of all modern theories of electromagnetic phenomena. On Faraday's uses of the lines of force, James Clerk Maxwell wrote that they show Faraday "to have been in reality a mathematician of a very high order--one from whom the mathematicians of the future may derive valuable and fertile methods."
Public service
Beyond his scientific research into areas such as chemistry, electricity, and magnetism at the Royal Institution, Faraday undertook numerous, and often time-consuming, service projects for private enterprise and the British government. This work included investigations of explosions in coal mines, being an expert witness in court, and the preparation of high-quality optical glass. In 1846, together with Charles Lyell, he produced a lengthy and detailed report on a serious explosion in the colliery at Haswell County Durham which killed 95 miners. Their report was a meticulous forensic investigation and indicated that coal dust contributed to the severity of the explosion. The report should have warned coal owners of the hazard of coal dust explosions, but the risk was ignored for over 60 years until the Senghenydd Colliery Disaster of 1913.
As a respected scientist in a nation with strong maritime interests, Faraday spent extensive amounts of time on projects such as the construction and operation of light houses and protecting the bottoms of ships from corrosion.
Faraday also was active in what would now be called environmental science, or engineering. He investigated industrial pollution at Swansea and was consulted on air pollution at the Royal Mint. In July of 1855, Faraday wrote a letter to The Times on the subject of the foul condition of the River Thames, which resulted in an oft-reprinted cartoon in Punch. (See also The Great Stink.)
Faraday assisted with planning and judging of exhibits for the Great Exhibition of 1851 in London. He also advised the National Gallery on the cleaning and protection of its art collection, and served on the National Gallery Site Commission in 1857.
Education was another area of service for Faraday. He lectured on the topic in 1854 at the Royal Institution, and in 1862 he appeared before a Public Schools Commission to give his views on education in Great Britain. Faraday also weighed in, negatively, on the public's fascination with table-turning, mesmerism, and seances, chastising both the public and the nation's educational system.
Faraday gave a successful series of lectures on the chemistry and physics of flames at the Royal Institution, entitled The Chemical History of a Candle. This was one of the earlier Christmas lectures for young people, which are still given each year. Between 1827 and 1860, Faraday gave the Christmas lecture a record nineteen times.
Later life
In June of 1832, the University of Oxford granted Faraday a Doctor of Civil Law degree (honorary). During his lifetime, Faraday rejected a knighthood and twice refused to become President of the Royal Society.
In 1848, as a result of representations by the Prince Consort, Michael Faraday was awarded a grace and favour house in Hampton Court, Surrey free of all expenses or upkeep. This was the Master Mason's House, later called Faraday House, and now No.37 Hampton Court Road. In 1858 Faraday retired to live there.
Faraday died at his house at Hampton Court on August 25, 1867. He turned down burial in Westminster Abbey, but he has a memorial plaque there, near Isaac Newton's tomb. Faraday was interred in the Sandemanian plot in Highgate Cemetery.
Quotations - "Nothing is too wonderful to be true if it be consistent with the laws of nature, and in such things as these, experiment is the best test of such consistency."
- "Work. Finish. Publish." — his advice to the young William Crookes
- "The important thing is to know how to take all things quietly."
- Regarding the hereafter, "Speculations? I have none. I am resting on certainties."
- "No wonder that my remembrance fails me, for I shall complete my 70 years next Sunday (the 22); -- and during these 70 years I have had a happy life; which still remains happy because of hope and content.
- Above the doorways of the Pfahler Hall of Science at Ursinus College in Collegeville, Pennsylvania, there is a stone inscription of a quote attributed to Michael Faraday which reads "but still try, for who knows what is possible..."
- "One day sir, you may tax it." Faraday's reply to William Gladstone, then British Minister of Finance, when asked of the practical value of electricity.
- "If you would cause your view ... to be acknowledged by scientific men; you would do a great service to science. If you would even get them to say yes or no to your conclusions it would help to clear the future progress. I believe some hesitate because they do not like their thoughts disturbed."
See also
Further reading
Biographies
- * Reprinted in 2005 by Adamant Media Corporation
- The British Electrical and Allied Manufacturers Association (1931). Faraday. R. & R. Clark, Ltd., Edinburgh, 1931.
Others
External links
Biographies-
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- by J. A. Crowther, London: Society for Promoting Christian Knowledge, 1920
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