Experimental determination of the laws of magneto-electric induction in different masses of the same metal, and of its intensity in different metals

1837 ◽  
Vol 3 ◽  
pp. 177-178
Keyword(s):  
Experimental Determination ◽  
Royal Society ◽  
Iron Wire ◽  
Electric Excitation ◽  
Electric Induction ◽  
Other Substances ◽  
The Difference ◽  
Experimental Researches

The reading of Mr. Christie’s paper was resumed and concluded. Mr. Faraday, in his valuable papers entitled “Experimental Researches in Electricity,” has advanced the proposition, that “when metals of different kinds are equally subject, in every circumstance, to magneto-electric induction, they exhibit exactly equal powers with respect to the currents which either are formed or tend to form in them;” and “that the same is probably the case in all other substances.” The author not being satisfied with the conclusiveness of the experiments adduced in support of this proposition,— in order to determine its correctness, subjected different metals directly to the same degree of magneto-electric excitation, in such a manner, that the currents excited in them should be in opposite directions (as was the case in Mr. Faraday’s experiment), and also that these opposing currents should have the same facility of transmission; so that the difference of their intensities, if any existed, might admit of measurement. He then minutely describes the apparatus he contrived with this view, and which consisted of helices of copper and of iron wire, covered with silk, each making sixty-five turns, but in opposite directions, and crossing each other alternately, and surrounding a cylinder of soft iron, which was rendered magnetic by the application of the large magnet belonging to the Royal Society, which the Council had placed at his disposal while engaged in these researches. The result of the experiment showed that the force of the currents from the copper helix considerably exceeded that from the iron helix, and appeared to be even more than double. By a modification of the apparatus, he found that the intensities of the currents in the two wires were very accurately proportional to their conducting powers; and hence the uniformity of the results obtained by Mr. Faraday is easily explicable.

III. Experimental researches in electricity. ─Twenty-fifth series

1851 ◽  
Vol 141 ◽  
pp. 29-84 ◽  
Keyword(s):  
Magnetic Force ◽  
Central Line ◽  
General View ◽  
Axial Line ◽  
Electric Induction ◽  
Other Substances ◽  
Iron Nickel ◽  
The Subject ◽  
Experimental Researches ◽  
As If

2797. The remarkable results given in a former series of these researches (2757. &c.) respecting the powerful tendency of certain gaseous substances to proceed either to or from the central line of magnetic force, according to their relation to other substances present at the same time, and yet the absence of all condensation or expansion of these bodies (2756.) which might be supposed to be consequent on such an amount of attractive or repulsive force as would be thought needful to produce this tendency and determination to particular places, have, upon consideration, led me to the idea, that if bodies possess different degrees of conducting power for magnetism, that difference may account for all the phenomena; and, further, that if such an idea be considered, it may assist in developing the nature of magnetic force. I shall therefore venture to think and speak freely on this matter for a while, for the purpose of drawing others into a consideration of the subject; though I run the risk, in doing so, of falling into error through imperfect experiments and reasoning. As yet, however, I only state the case hypothetically, and use the phrase conducting power as a general expression of the capability which bodies may possess of affecting the transmission of magnetic force; implying nothing as to how the process of conduction is carried on. Thus limited in sense, the phrase may be very useful, enabling us to take, for a time, a connected, consistent and general view of a large class of phenomena; may serve as a standard of meaning amongst them, and yet need not necessarily involve any error, inasmuch as whatever may be the principles and condition of conduction, the phenomena dependent on it must consist among themselves. 2798. If a medium having a certain conducting power occupy the magnetic field, and then a portion of another medium or substance be placed in the field having a greater conducting power, the latter will tend to draw up towards the place of greatest force, displacing the former. Such at least is the case with bodies that are freely magnetic, as iron, nickel, cobalt and their combinations (2357. 2363. 2367. &c.), and such a result is in analogy with the phenomena produced by electric induction. If a portion of still higher conducting power be brought into play, it will approach the axial line and displace that which had just gone there; so that a body having a certain amount of conducting power, will appear as if attracted in a medium of weaker power, and as if repelled in a medium of stronger power by this differential kind of action (2367. 2414.).

scholarly journals IX. On some hitherto undescribed optical properties of doubly refracting crystals.—Preliminary notice

1878 ◽  
Vol 26 (179-184) ◽  
pp. 384-386 ◽  
Keyword(s):  
Royal Society ◽  
Focal Point ◽  
The Body ◽  
Index Of Refraction ◽  
Double Refraction ◽  
Other Substances ◽  
The Subject ◽  
Microscopical Society ◽  
Royal Microscopical Society

In the Proceedings of the Royal Society (vol. xxiv. p. 393) Dr Royston-Pigott described a new refractometer to determine the index of refraction of liquids and other substances by means of the displacement of the focal point of an object seen through them with a low magnifying-power. Another paper on the subject was communicated by him to the Royal Microscopical Society, and subsequently published its Journal. After the reading of this paper I said that it appeared me probable that the same principle might be applied with advantage the determination of the index of refraction of minerals. The chief question was how to make the requisite measurements by means of such a addition to an ordinary microscope as would not in any way interfere with its general use for other purposes. This I accomplished by fixing graduated scale to the body of the microscope and a vernier to the supporting arm, so that the position of the focal point can be read off to within about 1/2000 of an inch. I described this arrangement and pointed out its value in connexion with mineralogy at a meeting of the Mineralogical Society last March, and an account of it was published in the Journal of the Society. I have since learned that a very similar addition was made to a microscope in Professor Clifton’s laboratory at Oxford some eight years ago, and used for the measurement of the index of refraction of glass, but no account of it was ever published. When I came to study the index of refraction of doubly refracting minerals I was very soon struck with the fact that, instead of seeing at one focus the two systems of lines at right angles to each other, they were sometimes quite invisible, or one set was seen at one focus, and the whether at a very different, as though they had been ruled on the two opposite sides of a piece of glass. These curious phenomena were exhibited at the soirée of the Royal Society on the 25th of April last, and Processor Stokes immediately examined the question theoretically, and found that they could be explained by, and might have been predicted from, the known laws of double refraction, though apparently no one had ever studied them, either theoretically or practically. We therefore decided to investigate the problem independently. I was to make the practical observations, and he to give the theoretical explanations, the results being kept separate, but communicated conjointly to the Royal Society.

scholarly journals VIII. The Bakerian Lecture.—Experimental of laws of magneto-electric induction in different masses of the same metal, and of Intensity in different metals

1833 ◽  
Vol 123 ◽  
pp. 95-142 ◽  
Keyword(s):  
Great Difficulty ◽  
The Other ◽  
Present Purpose ◽  
Electric Induction ◽  
Other Substances ◽  
The Subject ◽  
The Absolute ◽  
Experimental Researches

Mr. Faraday's highly interesting papers, entitled “Experimental Researches in Electricity,” having been referred to me, to report on, by the President and Council of this Society, I necessarily entered minutely into all the experiments and conclusions of the author, and the more so that I had had the advantage of witnessing many of the most important of these experiments. It is foreign to my present purpose to descant upon the value of Mr. Faraday’s discovery, or the merits of his communication ; the President and Council have marked their opinion of these by the award of the Copley Medal: but I may be permitted to state, that no one can concur more cordially than I do in the propriety of that award. Agreeing as I did generally with the author, both in the views which he took of the subject, and in the conclusions which he drew from his experiments, there was one, however, which I felt great difficulty in adopting, viz. “That when metals of different kinds are equally subject, in every circumstance, to magneto-electric induction, they exhibit exactly equal powers with respect to the currents which either are formed, or tend to form, in them :" and that “the same is probably the case in all other substances.” Although the experiments might appear to indicate that this was possibly the case, I did not consider them to be conclusive. The most conclusive experiment, that of two spirals, one of copper and the other of iron, transmitting opposite currents, was quite consistent with the absolute equality of the currents excited in copper and iron; but, at the same time, the apparent equality of the currents might be due to their inequality being counteracted by a corresponding inequality in the facility of transmission.

scholarly journals An experimental determination of the critical electron velocities for the production of radiation and ionisation on collision with argon atoms

1920 ◽  
Vol 97 (681) ◽  
pp. 1-23 ◽  
Keyword(s):  
Experimental Determination ◽  
Electric Current ◽  
Circular Hole ◽  
Royal Society ◽  
Tungsten Filament ◽  
Electron Collisions ◽  
Similar Investigation ◽  
Helium Atoms ◽  
Electric Effect

In the ‘Proceedings of the Royal Society’ for 1919 (A, vol. 95, p. 408) we have given an account of an investigation of the effects of electron collisions with helium atoms. The apparatus and method there described have been somewhat modified, and applied to a similar investigation with argon. With this gas Franck and Hertz came to the conclusion that ionisation occurs when the velocity of the colliding electrons is raised to 12 volts, but the method of experimenting used by them was not able to distinguish between ionisation of the gas and the photo-electric effect of radiation produced by the collisions. The main features of the apparatus used in the present research have been described in the earlier paper; the modifications introduced will be seen by reference to the diagrammatic view in fig. 1. A short tungsten filament, F, which could be heated to incandescence by an electric current, was used as the source of electrons. This was supported horizontally and about 1·5 mm. below the top of the platinum thimble, E, which was plane and circular, and had at its centre a circular hole 1·5 mm. in diameter.

III. On effects of retentiveness in the magnetisation of iron and steel. (preliminary notice.)

1883 ◽  
Vol 34 (220-223) ◽  
pp. 39-45 ◽  
Keyword(s):  
Magnetic Field ◽  
Royal Society ◽  
Wide Area ◽  
Iron And Steel ◽  
Iron Wire ◽  
Other Substances ◽  
Effects Of Stress ◽  
The Magnetic Field

The term Hysteresis was introduced in a paper, recently communicated to the Royal Society, to designate a peculiar action which was observed in the inquiry then recorded, and which had also presented itself in an earlier investigation—of the effects of stress on thermoelectric quality.f It was found that when a stretched iron wire was gradually loaded and unloaded the changes of thermoelectric quality lagged behind the changes of stress, so that curves exhibiting the relation of stress to thermoelectric quality during the putting on and taking off of the load were far from coincident, but inclosed between them a wide area. In prosecuting those experiments it occurred to me that there is much room for investigation of hysteresis § in the changes of magnetisation of iron and other substances produced by (1) change of the magnetic field; (2) change of stress; (3) change of temperature. In (2) and (3) two cases are to be considered :—First, when the substance is exposed to a constant magnetising force; second, when the magnetisation which is changed is wholly residual.

scholarly journals Experimental Determination of Lidar Overlap Profile Based on Dual Field-of-View High Spectral Resolution Lidar

2020 ◽  
Vol 237 ◽  
pp. 07014
Author(s):  
Nanchao Wang ◽  
Xue Shen ◽  
Yudi Zhou ◽  
Chong Liu ◽  
Yupeng Zhang ◽  
...  
Keyword(s):  
Experimental Determination ◽  
Spectral Resolution ◽  
Atmospheric Condition ◽  
Field Of View ◽  
High Spectral Resolution ◽  
Backscatter Coefficient ◽  
The Difference ◽  
High Level ◽  
High Spectral Resolution Lidar

This paper presents two approaches to calibrate the overlap factor under inhomogeneous atmospheric condition without critical assumption and delivers detailed analysis about the retrieval errors of overlap profile in High-Spectral-Resolution-Lidar (HSRL). The first method employs an additional optical subsystem with different field-of-view, that is dual field-of-view HSRL, for the retrieval of overlap profile. The second method takes advantage of the difference of the result between the HSRL and Klett method, that is about the retrieval of backscatter coefficient for uncorrected lidar signal, to correct overlap profile. Surprisingly, two methods show very high-level consistency and stability of the result. It is potential that this technique would be an excellent solution for experimental determination of lidar overlap in ground-based HSRL.

scholarly journals II. On the unit of length of a standard scale by Sir George Shuckburgh, appertaining to the Royal Society

1890 ◽  
Vol 47 (286-291) ◽  
pp. 186-189 ◽  
Keyword(s):  
Royal Society ◽  
Geodetic Survey ◽  
Standard Scale ◽  
Unit Of Length ◽  
The Difference ◽  
Made In ◽  
Modern Standard ◽  
A Share

In the determinations of the length of the seconds pendulum, which were made in London by Kater and at Greenwich by Sabine, and are described in the ‘Philosophical Transactions’ for 1818, 1829, and 1831, the distance between the upper and lower edges of the pendulum was measured off on a standard scale which had been con­structed by Sir George Shuckburgh. The scale had not been com­pared with any of the modern standard scales, but it had been preserved with much care with the instruments appertaining to the Royal Society. In the autumn of 1888, M. le Commandant Defforges, an officer of the French Geodetic Survey, came to England to take a share in operations for the determination of the difference in longitude between Greenwich and Paris, and also to determine the length of a French seconds pendulum at Greenwich.

V. An account of experiments made at the kew observatory for determining the true vacuum- and temperature-corrections to pendulum observations

1869 ◽  
Vol 17 ◽  
pp. 488-499
Keyword(s):  
Internal Friction ◽  
Royal Society ◽  
Experimental Methods ◽  
True Vacuum ◽  
Moving Body ◽  
Correct Determination ◽  
Fluid Body ◽  
The Difference ◽  
Made In

1. Pendulum-observations, whether undertaken for the purpose of obtaining unalterable standards of length or for physical and geodetic objects, are usually made in air or in a receiver, from which the air is partially or almost entirely withdrawn; and in order to render such observations, made at different places and by different observers, capable of intercomparison, they are, by means of a “correction for buoyancy,” reduced to a vacuum. It is well known that the most illustrious physicists and mathematicians have given a great deal of attention to a correct determination of the principles on which this reduction to a vacuum ought to be based, and of the actual resistance which such a body as a pendulum meets during its vibrations in a fluid body. Until some years ago, especially since the researches of General Sabine and Bessel, it was thought best to determine for every pendulum a certain constant by finding its vibrations in air at the usual pressure, and also in a receiver from which the air is as much as possible withdrawn; from the difference in the number of vibrations thus found the correction was then calculated on the assumption that this difference is proportional to the difference of density of the air. 2. In the pendulum-observations made at the Kew Observatory in connexion with the Great Trigonometrical Survey of India ( vide Proceedings of the Royal Society for 1865, No. 78) we adopted, for determining the necessary constant, the method first carried out by General Sabine, and of which a detailed account is given in the Philosophical Transactions for 1829, Part I. page 207 &c. But since our account has been published, two eminent physicists, Professor Clerk: Maxwell and Professor O. E. Meyer in Breslau, have independently investigated the internal friction in gases, and its effect upon bodies moving in them; and among the prominent results obtained by them is this, that the influence of the internal friction of a fluid on a moving body is not proportional to its density. However, for small differences of pressure, such as those experienced by General Sabine in his researches, the old method for determining the correction is sufficiently accurate; or again, if a series of such experiments as our own fundamental Kew observations for India be made at a very low pressure, say from ½ an inch to 1½ inch, the correction is itself a very small quantity; and the application of a more correct principle of reduction will not sensibly affect the ultimate results, because the difference between the true and approximate correction is in such a case extremely small. But if, as is the case in the Indian observations, experiments are made at higher and varying pressures, it is very desirable to apply experimental methods which will give the true correction.

To the Experimental Determination of the Spontaneous Polarization for the Silicon Carbide Polytypes

2013 ◽  
Vol 740-742 ◽  
pp. 459-462
Author(s):  
Sergey Yu. Davydov ◽  
Alexander A. Lebedev ◽  
O.V. Posrednik
Keyword(s):  
Silicon Carbide ◽  
Electric Field ◽  
Quantum Wells ◽  
Experimental Determination ◽  
External Electric Field ◽  
Spontaneous Polarization ◽  
Left And Right ◽  
The Difference ◽  
Local Levels

A NH/3C-SiC heterojunction and a heterostructur of the NH/3C/NH type (N = 2, 4, 6, 8) are consid-ered. Two possibilities are analyzed for heterojunctions, in which a Si or a C is the contact plane of the NH polytype. In this case, the energies of the quasi-local levels in the quantum wells at the interface will be different. With the difference of these energies measured, it is possible to determine the spon-taneous polarization inherent in the NH polytype. In the presence of a spontaneous polarization field, the quasi-local levels in the left- and right-hand quantum wells of the heterostructure have dif-ferent energies. It is shown that, if the heterostructur is placed in an external electric field, it is possible to determine the magnitude of the spontaneous polarization by calculating the different between the energies of these levels. Experimental ways to find by using the suggested theoretical scenario are discussed.

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