Michael Faraday

Michael Faraday, FRS (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.

Faraday studied the magnetic field around a conductor carrying a DC electric current. While conducting these studies, Faraday established the basis for the electromagnetic field concept in physics, subsequently enlarged upon by James Maxwell. He similarly discovered electromagnetic induction, diamagnetism, and laws of electrolysis. He established that magnetism could affect rays of light and that there was an underlying relationship between the two phenomena. 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.

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. Historians of science refer to him as the best experimentalist in the history of science. The SI unit of capacitance, thefarad, is named after him, as is the Faraday constant, the charge on a mole of electrons (about 96,485 coulombs). Faraday's law of induction states that magnetic flux changing in time creates a proportional electromotive force.

Faraday was the first and foremost Fullerian Professor of Chemistry at the Royal Institution of Great Britain, a life-time position.

Albert Einstein kept a photograph of Faraday on his study wall alongside pictures of Isaac Newton and James Clerk Maxwell.

Faraday's earliest chemical work was as an assistant to Humphry Davy. Faraday specifically studied chlorine, discovering 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 byThomas 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 that 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.

Faraday was highly religious; he was a member of the Sandemanian Church, a Christian sect founded in 1730 that demanded total faith and commitment. Biographers have noted that "a strong sense of the unity of God and nature pervaded Faraday's life and work."

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), and liquefying gases such as chlorine. Liquification of gases helped establish that gases are simply the vapours of liquids possessing a very low boiling-point, and gave a more solid basis to conceptions of molecular aggregation. 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 is best known for his work with 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 ofelectromagnetism, 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 that 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. 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, thereby removing him from electromagnetic research for several years.Faraday's breakthrough came when he wrapped two insulated coils of wire around an iron^{[verification needed]} 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 modelled mathematically by James Clerk Maxwell as 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.

From his initial electromagnetic discovery in 1821, Faraday continued his laboratory work exploring properties of materials and developing the 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 could find no such relationship. This lab followed similar work with light and magnets three years earlier with 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 from this optics work, Faraday continued publishing his experimental work (some of which related to EM) and conducted foreign correspondence with scientists (also working on EM) he previously met on his journeys about Europe with Davy. 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 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 (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 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 that dominated engineering and industry for the remainder of the 19th century.

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.