- Faraday , Michael
- (1791–1867) British physicist and chemistFaraday's father was a blacksmith who suffered from poor health and could only work irregularly. Faraday, who was born in Newington, knew real poverty as a child and his education was limited for he left school at the age of 13. He began work for a bookseller and binder in 1804 and was apprenticed the following year. His interest in science seems to have been aroused by his reading the 127-page entry on electricity in an Encyclopaedia Britannica he was binding and this stimulated him to buy the ingredients to make a Leyden jar and to perform some simple experiments. He joined the City Philosophical Society, which he attended regularly, broadening his intellectual background still further. The turning point in his life came when he attended some lectures by Humphry Davy at the Royal Institution in 1812. He took very full notes of these lectures, which he bound himself.By now he was no longer satisfied with his amateur experiments and evening lectures and wanted desperately to have a full-time career in science. He wrote to the President of the Royal Society, Joseph Banks, asking for his help in obtaining any post but received no reply. Faraday now had a little luck. Davy had had an accident and needed some temporary assistance. Faraday's name was mentioned and proved acceptable. While working with Davy he showed him the lecture notes he had taken and bound. When a little later, in 1813, a vacancy for a laboratory assistant arose, Davy remembered the serious young man and hired him at a salary of a guinea a week (less than Faraday had been earning as a bookbinder).Faraday was to spend the rest of his working life at the Royal Institution, from which he finally resigned in 1861. In 1815 he was promoted to the post of assistant and superintendent of the apparatus of the laboratory and meteorological collection. In 1825 he was made director of the laboratory and, in 1833, he was elected to the newly endowed Fullerian Professorship of Chemistry at the Royal Institution. He had earlier turned down the offer of the chair of chemistry at University College, London, in 1827.The paucity of the salary paid him was made up by Faraday with consultancy fees and a part-time lectureship he held at the Royal Military Academy, Woolwich. These extra sources took up his time and in 1831, when he was working as hard as he could on his electrical experiments, he gave up all his consultancies. This left him in some financial difficulties and moves were made to arrange for a government pension. He called on the prime minister of the day, Lord Melbourne, who made some sneering remark about such pensions being, in his view, a “gross humbug.” This was enough to make Faraday refuse the pension. In fact, Faraday was one of nature's great refusers. Apart from the pension and the chair at University College, he also refused a knighthood and, what must surely be a record, the presidency of the Royal Society, not once, but twice. Faraday also had strong views on awards – “I have always felt that there is something degrading in offering rewards for intellectual exertion, and that societies or academies, or even kings and emperors, should mingle in the matter does not remove the degradation.” He had become a fellow of the Royal Society in 1824 but not without some friction between himself and the president, Davy. He was asked to withdraw his application by Davy. Just why Davy behaved in this way is not clear. Some have seen it as jealousy by Davy of someone whose talents so clearly surpassed his own. There is no evidence of this but it is reasonably clear that when Faraday insisted on going ahead with his application Davy voted against him.Faraday's financial problems were solved when, in 1835, Melbourne apologized, enabling him to accept the pension. After his labors of the 1830s he suffered some kind of breakdown in 1841 and went into the country to rest. Just what was wrong is not known; he wrote in 1842 that he could see no visitors because of “ill health connected with my head.” For two years he did no work at all until in 1844 he seemed to be able to resume his experiments. Faraday continued to work but by the 1850s his creativity was in decline. He gave his last childrens' lectures at the Royal Institution in 1860 and resigned from it the following year, taking up residence in a house at Hampton Court made available to him by Prince Albert in 1858.Faraday's first real successes were made in chemistry. In 1823 he unwittingly liquefied chlorine. He was simply heating a chlorine compound in a sealed tube and noticed the formation of some droplets at the cold end. He realized that this was the result of both temperature and pressure and on and off over the years applied the method to other gases. In 1825 he discovered benzene (C6H6) when asked to examine the residue collecting in cylinders of illuminating gas; he called the new compound ‘bicarburet of hydrogen’ because he took its formula to be C2H. As a working chemist Faraday was one of the best analysts of his day. All his working life he was working and publishing as a chemist but in 1820 he also turned to a new field that was to dominate his life.Faraday had begun by accepting the view that electricity is composed of two fluids. It was common in the 18th century to see such phenomena as light, heat, magnetism, and electricity to be the result of weightless fluids. In 1820 Hans Christian Oersted made a most surprising discovery: he had found that a wire carrying a current is capable of deflecting a compass needle; the direction in which the needle turned depended on whether the wire was under or over the needle and the direction in which the current was flowing. André Marie Ampère found that two parallel wires attract each other if the current in each is traveling in the same direction but repel each other if the currents are moving in opposite directions. Finally François Arago discovered that a copper disk rotating freely on its own axis would produce rotation in a compass needle suspended over it.These phenomena were difficult to fit into fluid theories of electricity and magnetism. They enabled Faraday to make his first important discovery in 1821, that of electromagnetic rotation. A magnet was placed upright in a tube of mercury and secured firmly at the bottom with the pole of the magnet above the surface. A wire dipping into the mercury but free to rotate was suspended over the pole. When a current was passed through the mercury and through the wire, the wire rotated around the magnet. If the wire was secured and the magnet allowed to move, then the current caused the magnet to rotate. The first electric motor had been constructed.When Faraday published his results they were to cause him much distress. William Wollaston had spoken of the possibility of such rotation and many concluded that Faraday had stolen his ideas. Faraday was only too aware of the stories about him but found there was little he could do about them. It may well have been this that Davy thought disqualified him from membership of the Royal Society.In any case it was not really electromagnetic rotation that interested Faraday. All the new results involved the production of a magnetic force by an electric current and Faraday, with many others, was sure that it should also be possible to induce an electric current by magnetic action. He tried intermittently for ten years without success until in 1832 he hit upon an apparatus in which an iron ring was wound with two quite separate coils of wire. One was connected to a voltaic cell; the other to a simple galvanometer. He showed that on making and breaking the current in the cell circuit, the galvanometer momentarily registered the presence of a current in its circuit. The following few months were some of the most active of his life. He showed that the same results can be obtained without a battery: a magnet moved in and out of a coil of wire produced a current. A steady current could be produced by rotating a copper disk between the poles of a powerful magnet. His results were published in his Experimental Researches in Electricity, first series (1831).Faraday found this deeply satisfying for it reinforced one of his strongest convictions about nature “that the various forms under which the forces of matter are made manifest have one common origin.” That electricity and magnetism could interact made this view more plausible. At the time it was by no means clear that the various types of electricity – static, voltaic, animal, magnetic, and thermoelectric – were the same and Faraday spent the period 1833–34 on this problem publishing his results in the third series of his Experimental Researches.Faraday had also continued the work of Davy on electrolysis – i.e., on the chemical reaction produced by passing an electric current through a liquid. He applied his ideas on the quantity of electricity to this chemical effect and produced what are now known as Faraday's laws of electrolysis. By careful analysis he showed that the chemical action of a current is constant for a constant quantity of electricity. This was his first law, that equal amounts of electricity produce equal amounts of decomposition. In the second law he found that the quantities of different substances deposited on the electrode by the passage of the same quantity of electricity were proportional to their equivalent weights.In his explanations of magnetic and electrical phenomena Faraday did not use the fluid theories of the time. Instead he introduced the concept of lines of force (or tension) through a body or through space. (A similar earlier idea had been put forward by R.J. Boscovich with his picture of point atoms surrounded by shells of force.) Thus Faraday saw the connection between electrical and magnetic effects as vibrations of electrical lines communicated to magnetic lines. His experiments on induction were described in terms of the cutting of magnetic lines of force, which induces the electrical current. He explained electrical induction in dielectrics by the strain in ‘tubes of induction’ – and electrolysis was complete breakdown under such strain.Faraday was no mathematician, relying instead on his wonderful experimental skill and his imagination. His lines of force were taken up by others more skillful mathematically. In the latter half of the century Clerk Maxwell developed Faraday's ideas into a rigorous and powerful theory, creating an orthodoxy in physics that lasted until the time of Einstein. Faraday's greatness rests in his courage and insight in rejecting the traditional physics and creating an entirely new one. Few can compete with Faraday at the level of originality.One further effect discovered by Faraday lay in optics. His discovery of Faraday rotation in 1845 was one that gave him pleasure for it seemed to be further evidence for the unity of nature by showing that “magnetic force and light were proved to have a relation to each other.” Here, he showed that if polarized light is passed through a transparent medium in a magnetic field its plane of polarization will be rotated.Not the least of Faraday's achievements was as a lecturer and popularizer of science. In 1826 he started the famous Christmas lectures to children at the Royal Institution in London and gave 19 of these lecture courses. For most only the notes exist but a couple of lectures were taken down in shorthand and later published: The Chemical History of a Candle and Lectures on Various Forces of Matter. The children's Christmas lectures still continue to be given every year by eminent scientists.
Scientists. Academic. 2011.