Faraday Sentence Examples
At last, in 1845, Faraday attacked the old problem, but this time with complete success.
Faraday's term " electrode," literally " a way (650s) for electricity to travel along," might be well applied to designate the insulated conductor along which the electric messenger is despatched.
About the same time appeared his elaborate memoir, " On Faraday's Lines of Force," in which he gave the first indication of some of those extraordinary electrical investigations which culminated in the greatest work of his life.
The writer had the opportunity of perusing the MS. of " On Faraday's Lines of Force," in a form little different from the final one, a year before Maxwell took his degree.
Weber, which was found capable of explaining all the phenomena investigated by Ampere as well as the induction currents of Faraday.Advertisement
He also investigated the diamagnetic and paramagnetic properties of substances; and was keenly interested in the phenomena of electrochemical decomposition, accumulating much evidence in favour of Faraday's law and proposing a modified statement of it which was intended to cover certain apparent exceptions.
Faraday's next step was to pass the same current through different electrolytes in series.
Faraday examined also the electrolysis of certain fused salts such as lead chloride and silver chloride.
Since Faraday's time his laws have been confirmed by modern research, and in favourable cases have been shown to hold good with an accuracy of at least one part in a thousand.
The opposite parts of an electrolyte, which work their way through the liquid under the action of the electric forces, were named by Faraday the ions - the travellers.Advertisement
While it seems clear that the conduction in this case is carried on by ions similar to those of solutions, since Faraday's laws apply equally to both, it does not follow necessarily that semi-permanent dissociation is the only way to explain the phenomena.
This experiment suggested to Faraday the conception of ' r,?
Thomson (afterwards Lord Kelvin) in 1847, as the result of a mathematical investigation undertaken to explain Faraday's experimental observations.
But it was discovered by Faraday in 1845 that all substances, including even gases, are either attracted or repelled by a sufficiently powerful magnetic pole.
These are the " axial " and " equatorial " positions of Faraday.Advertisement
Now iron, nickel and cobalt all lose their magnetic quality when heated above certain critical temperatures which vary greatly for the three metals, and it was suspected by Faraday 3 as early as 1845 that manganese might really be a ferromagnetic metal having a critical temperature much below the ordinary temperature of the air.
The critical temperature (if there is one) was not reached in Faraday's experiment; possibly even the temperature of -250 C., which by the use of liquid hydrogen has now become accessible, might still be too high.
Michael Faraday's researches were begun in 1831 and continued for more than twenty years.
In 1873 James Clerk Maxwell published his classical Treatise on Electricity and Magnetism, in which Faraday's ideas were translated into a mathematical form.
He failed in both respects, and when Michael Faraday, who overheard a portion of his conversation with Davy on the subject, was subsequently more successful, he was inclined to assert the merit of priority, to which Faraday did not admit his claim.Advertisement
In 1824 the Royal Astronomical Society of London appointed a committee on the subject, the experimental' work being carried out by Faraday.
In 1868 he succeeded Faraday as Fullerian professor of chemistry at the Royal Institution, and in 1872 he was elected, in succession to Sir Benjamin Brodie, Waynflete professor of chemistry at Oxford, a chair he occupied for 40 years.
Faraday introduced the important and useful conception of lines and tubes of electric force.
Faraday expressed this fact by saying that no absolute electric charge could be given to matter.
Cavendish and subsequently Faraday discovered this fact, and the latter gave the name " specific inductive capacity," or " dielectric constant," to that quality of an insulator which determines the charge taken by a conductor embedded in it when charged to a given potential.Advertisement
The student will find it to be a great advantage to read through Faraday's three volumes entitled Experimental Researches on Electricity, as soon as he has mastered some modern elementary book giving in compact form a general account of electrical phenomena.
Faraday applied it to the preparation of extremely thin films of the metal.
This subject he was led to study by the experience of a colliery engineman, who noticed that he received a sharp shock on exposing one hand to a jet of steam issuing from a boiler with which his other hand was in contact, and the inquiry was followed by the invention of the "hydro-electric" machine, a powerful generator of electricity, which was thought worthy of careful investigation by Faraday.
Faraday was first able to liquefy ammonia.
A train of ideas which strongly impressed itself on Clerk Maxwell's mind, in the early stages of his theoretical views, was put forward by Lord Kelvin in 1858; he showed that the special characteristics of the rotation of the plane of polarization, discovered by Faraday in light propagated along a magnetic field, viz.
Now the electric force (P,Q,R) is the force acting on the electrons of the medium moving with velocity v; consequently by Faraday's electrodynamic law (P,Q,R) = (P',Q' - vc, R'+vb) where (P',Q',R') is the force that would act on electrons at rest, and (a,b,c) is the magnetic induction.
Hence many of his investigations were first described by Faraday in his Friday evening discourses at the Royal Institution.
Churches of this order were founded in Paisley, Glasgow, Edinburgh, Leith, Arbroath, Montrose, Aberdeen, Dunkeld, Cupar, Galashiels, Liverpool and London, where Michael Faraday was long an elder.
Faraday himself became apprenticed to a bookbinder.
Faraday took notes of these lectures, and afterwards wrote them out in a fuller form.
Faraday's earliest chemical work was in the paths opened by Davy, to whom he acted as assistant.
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 polarization of light when the glass was placed in the magnetic field, and also as the substance which was first repelled by the poles of the magnet.
But Faraday's chemical work, however important in itself, was soon completely overshadowed by his electrical discoveries.
Faraday was not there at the time, but coming in afterwards he heard the conversation on the expected rotation of the wire.
This first success of Faraday in electro-magnetic research became the occasion of the most painful, though unfounded, imputations against his honour.
Into these we shall not enter, referring the reader to the Life of Faraday, by Dr Bence Jones.
The thing cannot be done unless we adopt in some form Faraday's ingenious solution, by causing the current, in some part of its course, to divide into two channels, one on each side of the magnet, in such a way that during the revolution of the magnet the current is transferred from the channel in front of the magnet to the channel behind it, so that the middle of the magnet can pass across the current without stopping it, just as Cyrus caused his army to pass dryshod over the Gyndes by diverting the river into a channel cut for it in his rear.
During his first period of discovery, besides the induction of electric currents, Faraday established the identity of the electrification produced in different ways; the law of the definite electrolytic action of the current; and the fact, upon which he laid great stress, that every unit of positive electrification is related in a definite manner to a unit of negative electrification, so that it is impossible to produce what Faraday called "an absolute charge of electricity" of one kind not related to an equal charge of the opposite kind.
The first period of Faraday's electrical discoveries lasted ten years.
On the 3rd of November a new horseshoe magnet came home, and Faraday immediately began to experiment on the action in the polarized ray through gases, but with no effect.
The discovery of the magnetic rotation of the plane of polarized light, though it did not lead to such important practical applications as some of Faraday's earlier discoveries, has been of the highest value to science, as furnishing complete dynamical evidence that wherever magnetic force exists there is matter, small portions of which are rotating about axes parallel to the direction of that force.
The parents of Faraday belonged to the very small and isolated Christian sect which is commonly called after Robert Sandeman.
Faraday himself attended the meetings from childhood; at the age of thirty he made public profession of his faith, and during two different periods he discharged the office of elder.
And Faraday devised some simple apparatus which conclusively demonstrated that the movements were due to unconscious muscular action.
But Faraday's demonstration did little to stop the popular craze.
Faraday in 1820, but the effect had been known to exist for a long time previously.
Faraday was first able to obtain liquid chlorine.
The second dates from Volta's discovery to the discovery by Faraday in 1831 of the induction of electric currents and the creation of currents by the motion of conductors in magnetic fields, which initiated the era of modern electrotechnics.
In connexion with this subject he anticipated one of Faraday's The Electrical Researches of the Hon.
In it Oersted describes the action he considers is taking place around 2 Faraday discussed the chemical theory of the pile and arguments in support of it in the 8th and 16th series of his Experimental Researches on Electricity.
In 1821 Michael Faraday (1791-1867), who was destined later on to do so much for the science of electricity, discovered electromagnetic rotation, having succeeded in causing a wire conveying a voltaic current to rotate continuously round the pole of a permanent magnet.
Electric magnets of great power were soon constructed in this manner by Sturgeon, Joule, Henry, Faraday and Brewster.
Herschel, Peter Barlow and others, but did not receive a final explanation until after the discovery of electromagnetic induction by Faraday in 1831.
Faraday and others then discovered, as already mentioned, means to make the conductor conveying the current rotate round a magnetic pole, and Ampere showed that a magnet could be made to rotate on its own axis when a current was passed through it.
In 1831 Faraday began the investigations on electromagnetic induction which proved more fertile in far-reaching practical consequences than any of those which even his genius gave to the world.
Fully familiar with the fact that an electric charge upon one conductor could produce a charge of opposite sign upon a neighbouring conductor, Faraday asked himself whether an electric current passing through a conductor could not in any like manner induce an electric current in some neighbouring conductor.
The whole of Faraday's investigations on this subject can be summed up in the single statement that if a conducting circuit is placed in a magnetic field, and if either by variation of the field or by movement or variation of the form of the circuit the total magnetic flux linked with the circuit is varied, an electromotive force is set up in that circuit which at any instant is measured by the rate at which the total flux linked with the circuit is changing.
Amongst the memorable achievements of the ten days which Faraday devoted to this investigation was the discovery that a current could be induced in a conducting wire simply by moving it in the neighbourhood of a magnet.
Faraday's mind, however, revolted against this notion; he felt intuitively that these distance actions must be the result of unseen operations in the interposed medium.
All the space round magnets, currents and electric charges was therefore to Faraday the seat of corresponding lines of magnetic or electric force.
Space compels us to limit our account of the scientific work done by Faraday in the succeeding twenty years, in elucidating electrical phenomena and adding to the knowledge thereon, to the very briefest mention.
Faraday divided these researches into various series.
The voltameter provided a means of measuring quantity of electricity, and in the hands of Faraday and his successors became an appliance of fundamental importance.
The 8th series is occupied with a discussion of the theory of the voltaic pile, in which Faraday accumulates evidence to prove that the source of the energy of the pile must be chemical.
This discovery was made in November 1837 when Faraday had no knowledge of Cavendish's previous researches into this matter.
Faraday's ideas thus pressed upon electricians the necessity for the quantitative measurement of electrical phenomena.'
Lenz (1804-1865), 1 Amongst the most important of Faraday's quantitative researches must be included the ingenious and convincing proofs he provided that the production of any quantity of electricity of one sign is always accompanied by the production of an equal quantity of electricity of the opposite sign.
The phenomena connected with the propagation of electric signals by underground insulated wires had already engaged the attention of Faraday in 1854, who pointed out the Leyden-jar-like action of an insulated subterranean wire.
The work of Faraday from 1831 to 1851 stimulated and originated an immense mass of scientific research, but at the same time practical inventors had not been slow to perceive that it was capable of purely technical application.
Faraday's copper disk rotated between the poles of a magnet, and producing thereby an electric current, became the parent of 1 See also his Submarine Telegraphs (London, 1898).
The phenomena of light had compelled physicists to postulate a space-filling medium, to which the name ether had been given, and Henry and Faraday had long previously suggested the idea of an electromagnetic medium.
Maxwell never committed himself to a precise definition of the physical nature of electric displacement, but considered it as defining that which Faraday had called the polarization in the insulator, or, what is equivalent, the number of lines of electrostatic force passing normally through a unit of area in the dielectric. A second fundamental conception of Maxwell was that the electric displacement whilst it is changing is in effect an electric current, and creates, therefore, magnetic force.
A second relation connecting magnetic and electric force is 3 The first paper in which Maxwell began to translate Faraday's conceptions into mathematical language was " On Faraday's Lines of Force," read to the Cambridge Philosophical Society on the 10th of December 1855 and the I ith of February 1856.
The two-fluid theory may be said to have held the field until the time when Faraday began his researches on electricity.
Since Faraday was well aware that even a good vacuum can act as a dielectric, he recognized that the state he called dielectric polarization could not be wholly dependent upon the presence of gravitative matter, but that there must be an electromagnetic medium of a supermaterial nature.
Berzelius early in the 19th century had advanced the hypothesis that chemical combination was due to electric attractions between the electric charges carried by chemical atoms. The notion, however, that electricity is atomic in structure was definitely put forward by Hermann von Helmholtz in a well-known Faraday lecture.
Lord Kelvin showed that Faraday's discovery demonstrated that some form of rotation was taking place along lines of magnetic force when passing through a medium.'
Faraday discovered the existence of a dark space round the negative electrode which is usually known as the " Faraday dark space."
Faraday had shown that the passage of electrical action involved time, and he also asserted that electrical phenomena are brought about by changes in intervening non-conductors or dielectric substances.
Faraday observed that a large drop of mercury, resting on the flat bottom of a vessel containing dilute acid, changes its form in a remarkable way when connected with one of the electrodes of a battery, the other electrode being placed in the acid.
He also published biographies of Reis, Faraday and Kelvin.
In October he started with his wife for a continental tour, and with them, as "assistant in experiments and writing," went Michael Faraday, who in the previous March had been engaged as assistant in the Royal Institution laboratory.
In 1823, when Faraday liquefied chlorine, he read a paper which suggested the application of liquids formed by the condensation of gases as mechanical agents.
He wrote, in addition to several scientific books and a number of papers in scientific periodicals, The Life and Letters of Faraday (1870).
But a far more important instance of induced activity is afforded by Michael Faraday's discovery of the rotary polarization connected with a magnetic field.
At the Royal Institution Faraday held a unique position, and was feeling his way almost alone.
Faraday, can you remember me shewing you a rather splendid 108 carat diamond my father obtained from Dan Eliason?
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Faraday's discovery of the induced current produced by passing a magnet through a helix of wire forming part of a closed circuit was laid hold of in the telegraph of Gauss and Weber, and this application was at the request of Gauss taken up by Steinheil, who brought it to considerable perfection.
He began by reading, with the most profound admiration and attention, the whole of Faraday's extraordinary self-revelations, and proceeded to translate the ideas of that master into the succinct and expressive notation of the mathematicians.
Faraday's lines not only show the direction of the magnetic force, but also serve to indicate its magnitude or strength in different parts of the field.
The lines presented to the eye by the scattered filings are too vague and ill-defined to give a satisfactory indication of the field-strength (see Faraday, Experimental Researches, § 3 2 37) though they show its direction clearly enough.
Faraday independently recognized the necessity for mechanical agitation of the molten glass in order to ensure homogeneity, and to facilitate his manipulations he worked with dense lead borate glasses which are very fusible, but have proved too unstable for ordinary optical purposes.
Trans., 1876, 166 [ii.], P. 489, where it is shown that tapping the glass of a Leyden jar permits the reappearance of the residual charge; " On the Residual Charge of 2 See Faraday, Experimental Researches, vol.
Faraday, however, showed long subsequently that to bestow upon the indications of such an electroscope definite meaning 1 See the English translation by the Gilbert Club of Gilbert's De magnete, p. 49 (London, 1900).
Faraday first succeeded by the simple but ingenious device of using a light magnetic needle tethered flexibly to the bottom of a cup containing mercury so that one pole of the magnet was just above the surface of the mercury.
James Clerk Maxwell (1831-1879) entered on his electrical studies with a desire to ascertain if the ideas of Faraday, so different from those of Poisson and the French mathematicians, could be made the foundation of a mathematical method and brought under the power of analysis.3 Maxwell started with the conception that all electric and magnetic phenomena are due to effects taking place in the dielectric or in the ether if the space be vacuous.
Only solar power stands out as a way of making electricity without Faraday's discovery.
He also carried out many experiments in magneto-optics, and succeeded in showing, what Faraday had failed to detect, the rotation under the influence of magnetic force of the plane of polarization in certain gases and vapours.
The investigation of Carpenter on unconscious cerebration and of Faraday on unconscious muscular action showed early in the movement that it was not necessary to look outside the medium's own personality for the explanation of even intelligent communications unconsciously conveyed through table-tilting, automatic writing and trance-speaking - provided the matter communicated was not beyond the range of the medium's own knowledge or powers.
His great object, as it was also the great object of Faraday, was to overturn the idea of action at a distance.
He was a most prolific writer, 364 papers appearing under his name in the Royal Society's Catalogue, and he carried on a large correspondence with other men of science, such as Berzelius, Faraday, Liebig and Wohler.
Hydrochloric acid was carefully investigated at about this time by Davy, Faraday and Gay Lussac, its composition and the elementary nature of chlorine being thereby established.
The first exact quantitative study of electrolytic phenomena was made about 1830 by Michael Faraday (Experimental Researches, 1833).
Acting on this view, Faraday set himself to examine the relation between the flow of electricity round the circuit and the amount of chemical decomposition.
This description, quoted from James Clerk Maxwell's article in the 9th edition of the Encyclopaedia Britannica, represents the historical position of the subject up till about 1860, when Maxwell began those constructive speculations in electrical theory, based on the influence of the physical views of Faraday and Lord Kelvin, which have in their subsequent development largely transformed theoretical physics into the science of the aether.
Henry Cavendish had before 1773 discovered that glass, wax, rosin and shellac have higher specific inductive capacities than air, and had actually determined the numerical ratios of these capacities, but this was unknown both to Faraday and to all other electricians of his time, since Cavendish's Electrical Researches remained unpublished till 1879.
Faraday had for a long time kept in view the possibility of using a ray of polarized light as a means of investigating the condition of transparent bodies when acted on by electric and magnetic forces.
In the following May he was chosen professor of natural philosophy at the Royal Institution, a post which exactly suited his striking gifts and made him a colleague of Faraday, whom in 1866 he succeeded as scientific adviser to the Trinity House and Board of Trade, and in 1867 as superintendent of the Royal Institution.
His reverent attachment to Faraday is beautifully manifested in his memorial volume called Faraday as a Discoverer (1868).