Michael Faraday (22 September 1791 - 25 August 1867) was an English chemist and physicist (or natural philosopher, in the terminology of the time) who contributed to the fields of electromagnetism and electrochemistry. Breakthroughs made by Faraday have contributed to the history of the cell / mobile phone.
Although Faraday received little formal education and knew little of higher mathematics such as calculus, he was one of the most influential scientists in history, and is often referred to by historians of science as being the best experimentalist in the history of science. It was on account of his research regarding the magnetic field around a conductor carrying a DC electric current that Faraday established the basis for the concept of the electromagnetic field in physics, which was subsequently enlarged upon by James Clerk Maxwell. Faraday established that magnetism could affect rays of light and that there was an underlying relationship between the two phenomena. He similarly discovered the principle of electromagnetic induction, diamagnetism, and the laws of electrolysis. His inventions of electromagnetic rotary devices formed the foundation of electric motor technology, and it was largely due to his efforts that electricity became viable for use in technology.
As a chemist, Faraday discovered benzene, investigated the clathrate hydrate of chlorine, invented an early form of the Bunsen burner and the system of oxidation numbers, and popularised terminology such as anode, cathode, electrode, and ion. Faraday ultimately became the first and foremost Fullerian Professor of Chemistry at the Royal Institution of Great Britain, which was a life-time position.
Faraday was an excellent experimentalist who conveyed his ideas in clear and simple language; his mathematical abilities, however, 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 them with a set of equations that lay at the base of all modern theories regarding electromagnetic phenomena. On Faraday's uses of the lines of force, 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."
It is said that Albert Einstein kept a photograph of Faraday on his study wall, alongside the photographs of Isaac Newton and James Clerk Maxwell.
The SI unit of capacitance, the farad, is named in his honor.
Faraday's Early Life
Faraday was born in Newington Butts, which is now part of the London Borough of Southwark, but which was then a suburban part of Surrey. His family was not well off; his father, James, was a member of the Glassite sect of Christianity. James Faraday moved his wife and two children to London during the winter of 1790 from Outhgill in Westmorland, where he had been an apprentice to the village blacksmith. Michael was born in the autumn (fall) of that year. The young Michael Faraday, who was the third of four children, having only the most basic of school educations, had to mainly educate himself. At fourteen he became the apprentice to George Riebau, a local bookbinder and bookseller in Blandford Street. During his seven-year apprenticeship he read many books, including Isaac Watts' The Improvement of the Mind, and he enthusiastically implemented the principles and suggestions contained therein. At this time he also developed an interest in science, especially in electricity. Faraday was particularly inspired by the book Conversations on Chemistry by Jane Marcet.
In 1812, at the age of twenty, and at the end of his apprenticeship, Faraday attended lectures by the eminent English chemist Humphry Davy of the Royal Institution and Royal Society, and John Tatum, founder of the City Philosophical Society. Many of the tickets for these lectures were given to Faraday by William Dance, who was one of the founders of the Royal Philharmonic Society. Faraday subsequently sent Davy a three hundred page book based on notes that he had taken during these lectures. Davy's reply was immediate, kind, and favourable. When Davy damaged his eyesight in an accident with nitrogen trichloride, he decided to employ Faraday as a secretary. When one of the Royal Institution's assistants, John Payne, was sacked, Sir Humphry Davy was asked to find a replacement, and appointed Faraday as Chemical Assistant at the Royal Institution on 1 March 1813.
In the class-based English society of the time, Faraday was not considered a gentleman. When Davy set out on a long tour of the continent in 1813-15, his valet did not wish to go. Instead, Faraday went as Davy's scientific assistant, and was asked to act as Davy's valet until a replacement could be found in Paris. Faraday was forced to fill the role of valet as well as assistant throughout the trip. Davy's wife, Jane Apreece, refused to treat Faraday as an equal (making him travel outside the coach, eat with the servants, and so on), and made Faraday so miserable that he contemplated returning to England alone and giving up science altogether. The trip did, however, give him access to the scientific elite of Europe and exposed him to a host of stimulating ideas.
Faraday was a devout Christian, with his Sandemanian denomination being an offshoot of the Church of Scotland. Well after his marriage, he served as Deacon and for two terms as an Elder in the meeting house of his youth. His church was located at Paul's Alley in the Barbican. This meeting house was relocated in 1862 to Barnsbury Grove, Islington, and it was in this North London location that Faraday served the final two years of his second term as Elder prior to his resignation from that post. Biographers have noted that "a strong sense of the unity of God and nature pervaded Faraday's life and work."
Faraday married Sarah Barnard (1800-1879) on 12 June 1821. They met through their families at the Sandemanian church, and he confessed his faith to the Sandemanian congregation the month after they were married. They had no children.
Faraday's earliest chemical work was as an assistant to Humphry Davy. Faraday was specifically involved in the study of chlorine; he discovered two new compounds of chlorine and carbon. He also conducted the first rough experiments on the diffusion of gases, a phenomenon that was first pointed out by John Dalton, and the physical importance of which was more fully brought to light by Thomas Graham and Joseph Loschmidt. Faraday succeeded in liquefying several gases, investigated the alloys of steel, and produced several new kinds of glass intended for optical purposes. A specimen of one of these heavy glasses subsequently became historically important; when the glass was placed in a magnetic field Faraday determined the rotation of the plane of polarisation of light. This specimen was also the first substance found to be repelled by the poles of a magnet.
Faraday invented an early form of what was to become the Bunsen burner, which is in practically use in science laboratories around the world 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), and liquefying gases such as chlorine. The liquifying of gases helped to establish that gases are the vapours of liquids possessing a very low boiling-point, and gave a more solid basis to the concept of molecular aggregation. In 1820 Faraday reported the first synthesis 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 is also responsible for discovering the laws of electrolysis, and for popularizing terminology such as anode, cathode, electrode, and ion, terms proposed in large part 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 is best known for his work regarding electricity and magnetism. His first recorded experiment 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, 12 July 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". One of these, now known as the homopolar motor, caused a continuous circular motion that was engendered by the circular magnetic force around a wire that extended into a pool of mercury wherein was placed a magnet; the wire would then rotate around the magnet if supplied with current from a chemical battery. These experiments and inventions formed the foundation of modern electromagnetic technology. In his excitement, Faraday published results without acknowledging his work with either Wollaston or Davy. The resulting controversy within the Royal Society strained his mentor relationship with Davy and may well have contributed to Faraday's assignment to other activities, which consequently prevented his involvement in electromagnetic research for several years.
From his initial discovery in 1821, Faraday continued his laboratory work, exploring electromagnetic properties of materials and developing requisite experience. In 1824, Faraday briefly set up a circuit to study whether a magnetic field could regulate the flow of a current in an adjacent wire, but he found no such relationship. This experiment followed similar work conducted with light and magnets three years earlier that yielded identical results. During the next seven years, Faraday spent much of his time perfecting his recipe for optical quality (heavy) glass, boro-silicate of lead, which he used in his future studies connecting light with magnetism. In his spare time, Faraday continued publishing his experimental work on optics and electromagnetism; he conducted correspondence with scientists, who he had met on his journeys across Europe with Davy, and who were also working on electromagnetism. Two years after the death of Davy, 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 now 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 that 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 modeled mathematically by James Clerk Maxwell as Faraday's law, which subsequently became one of the four Maxwell equations, and which have in turn evolved into the generalization known today as field theory. Faraday would later use the principles he had discovered 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, and so on. He concluded that, contrary to the 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 (current and voltage) 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 the eventual acceptance of his proposition by the scientific community. Faraday's concept of lines of flux emanating from charged bodies and magnets provided a way to visualize electric and magnetic fields; that conceptual model was crucial for the successful development of the electromechanical devices that dominated engineering and industry for the remainder of the 19th century.
In 1845, Faraday discovered that many materials exhibit a weak repulsion from a magnetic field: a phenomenon he termed diamagnetism.
Faraday also discovered that the plane of polarization of linearly polarized light can be rotated by the application of an external magnetic field aligned in the direction which 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".
In 1862 Faraday used a spectroscope to search for a different alteration of light, the change of spectral lines by an applied magnetic field. Unfortunately, the equipment available to him was insufficient for a definite determination of spectral change. Pieter Zeeman later used an improved apparatus enabling him to better study the same phenomenon. He published his results in 1897 and received the 1902 Nobel Prize in Physics for his success. In both his 1897 paper and his Nobel acceptance speech, Zeeman made reference to Faraday's work.
An external electrical field causes the charges to rearrange, which cancels the field inside.
In his work on static electricity, Faraday's ice pail experiment demonstrated that the charge resided only 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.
You can find out more about the life and work of Michael Faraday here: http://en.wikipedia.org/wiki/Michael_Faraday.