Home » Electronic Engineering History » Michael Faraday

Michael Faraday


Faraday

Michael Faraday, (22 September 1791 – 25 August 1867) was an English scientist who contributed to the fields of electromagnetism and electrochemistry. His main discoveries include those of electromagnetic induction, diamagnetism and electrolysis.

Although Faraday received little formal education, he was one of the most influential scientists in history. It was by his research on the magnetic field around a conductor carrying a direct current that Faraday established the basis for the concept of the electromagnetic field in physics. Faraday also established that magnetism could affect rays of light and that there was an underlying relationship between the two phenomena.[1][2] 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 practical 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, a lifetime 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. James Clerk Maxwell took the work of Faraday and others, and summarized it in a set of equations that is accepted as the basis of all modern theories of 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.”[3] The SI unit of capacitance, the farad, is named in his honour.

Albert Einstein kept a picture of Faraday on his study wall, alongside pictures of Isaac Newton and James Clerk Maxwell.[4] Physicist Ernest Rutherford stated; “When we consider the magnitude and extent of his discoveries and their influence on the progress of science and of industry, there is no honour too great to pay to the memory of Faraday, one of the greatest scientific discoverers of all time”.[

Faraday was born in Newington Butts,[6] which is now part of the London Borough of Southwark, but which was then a suburban part of Surrey.[7] 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.[8] Michael was born the autumn of that year. The young Michael Faraday, who was the third of four children, having only the most basic school education, had to educate himself.[9] At fourteen he became the apprentice to George Riebau, a local bookbinder and bookseller in Blandford Street.[10] 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.[11][12]

In June 1832, the University of Oxford granted Faraday a Doctor of Civil Law degree (honorary). During his lifetime, he was offered a knighthood in recognition for his services to science, which he turned down on religious grounds, believing it was against the word of the Bible to accumulate riches and pursue worldly reward, stating he preferred to remain “plain Mr Faraday to the end”.[18] He twice refused to become President of the Royal Society.[19] He was elected a foreign member of the Royal Swedish Academy of Sciences in 1838, and was one of eight foreign members elected to the French Academy of Sciences in 1844.[20]

Michael_Faraday

Faraday suffered a nervous breakdown in 1839 but eventually returned to his electromagnetic investigations.[21] In 1848, as a result of representations by the Prince Consort, Faraday was awarded a grace and favour house in Hampton Court in Middlesex, 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.[22]

When asked by the British government to advise on the production of chemical weapons for use in the Crimean War (1853–1856), Faraday refused to participate citing ethical reasons.[23]

Faraday died at his house at Hampton Court on 25 August 1867, aged 75.[24] He had previously turned down burial in Westminster Abbey, but he has a memorial plaque there, near Isaac Newton’s tomb. Faraday was interred in the dissenters’ (non-Anglican) section of Highgate Cemetery

Faraday is best known for his work regarding electricity and magnetism. His first recorded experiment was the construction of a voltaic pile with seven ha’penny coins, 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).

One of Faraday’s 1831 experiments demonstrating induction. The liquid battery (right) sends an electric current through the small coil (A). When it is moved in or out of the large coil (B), its magnetic field induces a momentary voltage in the coil, which is detected by the galvanometer (G).

Electromagnetic rotation experiment of Faraday, ca. 1821[33]

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.[2] 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.[34][35]

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.[36] This experiment followed similar work conducted with light and magnets three years earlier that yielded identical results.[37][38] During the next seven years, Faraday spent much of his time perfecting his recipe for optical quality (heavy) glass, borosilicate of lead,[39] which he used in his future studies connecting light with magnetism.[40] In his spare time, Faraday continued publishing his experimental work on optics and electromagnetism; he conducted correspondence with scientists whom he had met on his journeys across Europe with Davy, and who were also working on electromagnetism.[41] Two years after the death of Davy, in 1831, he began his great series of experiments in which he discovered electromagnetic induction, recording in his laboratory diary on 28 October 1831 he was; “making many experiments with the great magnet of the Royal Society”.[42]

 

English chemists Michael Faraday (left) and John Daniell (right), credited as founders of electrochemistry today.

A diagram of Faraday’s iron ring-coil apparatus

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.[2] This phenomenon is now known as mutual induction.[43] 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 modelled 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 and the electric motor.

In 1832, 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 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.[2]

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.

Diamagnetism

In 1845, Faraday discovered that many materials exhibit a weak repulsion from a magnetic field: a phenomenon he termed diamagnetism.[45]

Faraday also discovered that the plane of polarization of linearly polarized light can be rotated by the application of an external magnetic field aligned with the direction in 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“.[46]

Later on in his life, in 1862, Faraday used a spectroscope to search for a different alteration of light, the change of spectral lines by an applied magnetic field. The equipment available to him was, however, insufficient for a definite determination of 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[47] and his Nobel acceptance speech,[48] Zeeman made reference to Faraday’s work.

Michael_Faraday_statue_AB

Faraday cage

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

Source : Wikipedia

Leave a Reply

Your email address will not be published. Required fields are marked *

*

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>