scholarly journals Experimental researches in electricity

1851 ◽  
Vol 5 ◽  
pp. 567-569 ◽  
Keyword(s):  
Electric Current ◽  
Magnetic Force ◽  
Magnetic Forces ◽  
Magnetic Action ◽  
Long Time ◽  
Intimate Relation ◽  
Combined Action ◽  
The One ◽  
Experimental Researches ◽  
Fundamental Experiment

For a long time past the author had felt a strong persuasion, derived from philosophical considerations, that among the several powers of nature which in their various forms of operation on matter produce different classes of effects, there exists an intimate relation; that they are connected by a common origin, have a reciprocal dependence on one another, and are capable, under certain conditions, of being converted the one into the other. Already have electricity and magnetism afforded evidence of this mutual convertibility; and in extending his views to a wider sphere, the author became convinced that these powers must have relations with light also. Until lately his endeavours to detect these relations were unsuccessful; but at length, on instituting a more searching interrogation of nature, he arrived at the discovery recorded in the present paper, namely, that a ray of light may be electrified and magnetized; and that lines of magnetic force may be rendered luminous. The fundamental experiment revealing this new and important fact, which establishes a link of connexion between two great departments of nature, is the following. A ray of light issuing from an Argand lamp is first polarized in the horizontal plane by reflexion from a glass mirror, and then made to pass, for a certain space, through glass composed of silicated borate of lead, on its emergence from which it is viewed through a Nichol's eye-piece, capable of revolving on a horizontal axis, so as to intercept the ray, or allow it to be transmitted, alternately, in the different phases of its revolution. The glass through which the ray passes, and which the author terms the diamagnetic , is placed between the two poles of a powerful electro-magnet, arranged in such a position as that the line of magnetic forces resulting from their combined action shall coincide with, or differ but little from the course of the ray in its passage through the glass. It was then found that if the eye-piece had been so turned as to render the ray invisible to the observer looking through the eye-piece before the electric current had been established, it becomes visible whenever, by the completion of the circuit, the magnetic force is in operation; but instantly becomes again invisible on the cessation of that force by the interruption of the circuit. Further investigation showed that the magnetic action causes the plane of polarization of the polarized ray to rotate, for the ray is again rendered visible by turning the eye-piece to a certain extent; and that the direction of the rotation impressed upon the ray, when the magnetic influence is issuing from the south pole, and proceeding in the same direction as the polarized ray, is right-handed, or similar to that of the motion of the hands of a watch, as estimated by an observer at the eye-piece. The direction in which the rotation takes place will, of course, be reversed by reversing either the course of the ray or the poles of the magnet. Hence it follows that the polarized ray is made to rotate in the same direction as the currents of positive electricity are circulating, both in the helices composing the electro-magnet, and also in the same direction as the hypothetical currents, which, according to Ampere’s theory, circulate in the substance of a steel magnet. The rotatory action was found to be always directly proportional to the intensity of the magnetic force, but not to that of the electric current; and also to be proportional to the length of that portion of the ray which receives the influence. The interposition of substances which occasion no disturbance of the magnetic forces, produces no change in these effects. Magnets consisting only of electric helices act with less power than when armed with iron, and in which magnetic action is consequently more strongly developed.

scholarly journals XI. Experimental researches in electricity.—Twenty-ninth series

1852 ◽  
Vol 142 ◽  
pp. 137-159 ◽  
Keyword(s):  
Electric Current ◽  
Magnetic Force ◽  
Equal Proportion ◽  
Magnetic Forces ◽  
The Earth ◽  
Fine Wire ◽  
Pass Through ◽  
Experimental Researches ◽  
Experimental Indication ◽  
Equal Power

3177- The proposition which I have made to use the induced magneto-electric current as an experimental indication of the presence, direction and amount of magnetic forces (3074.), makes it requisite that I should also clearly demonstrate the principles and develope the practice necessary for such a purpose; and especially that I should prove that the amount of current induced is precisely proportionate to the amount of lines of magnetic force intersected by the moving wire, in which the electric current is generated and appears (3082, 3109.). The proof already given is, I think, sufficient for those who may repeat the experiments; but in order to accumulate evidence, as is indeed but proper in the first announcement of such a proposition, I proceeded to experiment with the magnetic power of the earth, which presents us with a field of action, not rapidly varying in force with the distance, as in the case of small magnets, but one which for a given place may be considered as uniform in power and direction; for if a room be cleared of all common magnets, then the terrestrial lines of magnetic force which pass through it, have one common direction, being that of the dip, as indicated by a free needle or other means, and are in every part in equal proportion or quantity, i. e . have equal power. Now the force being the same everywhere, the proportion of it to the current evolved in the moving wire is then perhaps more simply and directly determined, than in the case where, a small magnet being employed, the force rapidly changes in amount with the distance. i. Galvanometer . 3178. For such experimental results as I now propose to give, I must refer to the galvanometer employed and the precautions requisite for its proper use. The instrument has been already described in principle (3123.), and a figure of the conductor which surrounds the needles, given. This conductor may be considered as a square copper bar, 0·2 of an inch in thickness, which passes twice round the plane of vibration of each of the needles forming the astatic combination, and then is continued outwards and terminates in two descending portions, which are intended to dip into cups of mercury. As both the needles are within the convolutions of this bar, an indicating bristle or fine wire of copper is fixed parallel to, and above them upon the same axis, and this, in travelling over the usual graduated circle, shows the place and the extent of vibration or swing of the needles below. The suspension is by cocoon silk, and in other respects the instrument is like a good ordinary galvanometer.

scholarly journals Integrals of the equations of electrodynamics with to the electric constants of a transparent medium

1926 ◽  
Vol 113 (764) ◽  
pp. 237-253 ◽  
Keyword(s):  
Electric Current ◽  
Current Distribution ◽  
Magnetic Force ◽  
Small Radius ◽  
Transparent Medium ◽  
Electric Force ◽  
Present Communication ◽  
Magnetic Current ◽  
Magnetic Forces ◽  
Equations Of Electrodynamics

Integrals of the equations of propagation of electrical disturbances have been given by the present writer which express the electric and magnetic forces at any point outside a surface enclosing all the sources in terms of an electric current distribution and a magnetic current distribution over the surface. The result for a source at a point can be obtained by taking as the surface a sphere of very small radius with its centre at the point. This suggests that the equations representing Faraday’s laws can be written 1/V 2 ∂X/∂ t +4π i x = ∂ϒ/∂ y – ∂β/∂ z , 1/V 2 ∂X/∂ t + 4π i v =∂∝/∂ z – ∂ϒ/∂ x , 1/V 2 ∂z/∂ t – 4π i z = ∂β/∂ x – ∂∝/∂ y (1) – ∂∝/∂ t + 4π m x = ∂z/∂ y – ∂Y/∂y, – ∂β/∂t + 4π my = ∂X/∂ z – ∂Z/∂ x , – ∂ϒ/∂ t + 4π mz ∂Y/∂ x – ∂X/∂ y , (2) where X, Y, Z are the components of the electric force, α, β, γ are the components of the magnetic force, i x , i y , i z are the components of an electric current distribution, and m x , m y , m z are the components of a magnetic current distribution throughout the space. The object of the present communication is to express X, Y, Z, α, β, γ in terms of the electric current and magnetic current distributions and to apply the result to the discussion of the electric constants of a transparent medium. It is convenient to take instead of equations (1) and (2) the following equations, which include (1) and (2) as a particular case

II. Experimental researches in electricity.-twenty-second series (continued)

1849 ◽  
Vol 139 ◽  
pp. 19-41 ◽  
Keyword(s):  
Electric Current ◽  
The Body ◽  
Pure Zinc ◽  
Muriatic Acid ◽  
Magnetic Action ◽  
Original Direction ◽  
The Masses ◽  
Close Form ◽  
Magnetic Poles ◽  
Experimental Researches

2535. Zinc.—Plates of zinc broken out of crystallized masses gave irregular indications, and, being magnetic from the impurity in them, the effects might be due entirely to that circumstance. Pure zinc was thrown down electro-chemically on platina from solutions of the chloride and the sulphate. The former occurred in ramifying dendritic associations of small crystal; the latter in a compact close form. Both were free from magnetic action and freely diamagnetic, but neither showed any trace of the magnecrystallic action. 2536. Titanium.—Some good crystals of titanium obtained from the bottom of an iron furnace, were cleansed by the alternate action of acids and fluxes until as clear from iron as I could procure them. They were bright, well-formed and magnetic (2371), and contained iron, I think, diffused through their whole mass, for nitro-muriatic acid, by long boiling, continually removed titanium and iron from them. These crystals had a certain magnetic property which I am inclined to refer to their crystalline condition. When between the poles of the electro-magnet, they set; and when the electric current was discontinued, they still set between the poles of the enfeebled magnet as they did before. If left to itself a crystal always took the same position, showing that it was constantly rendered magnetic in the same direc­tion. But if a crystal was placed and kept in another position between the magnetic poles whilst the electric current was on, and afterwards the current suspended, and then the crystal set free, it pointed between the poles of the enfeebled magnet in this new direction; showing that the magnetism was in a different direction in the body of the crystal to that which it had before. If now the magnet were reinvigorated by the electric current, the crystal instantly spun round and took a magnetic state in the first or original direction. The crystals could in fact become magnetized in any direction, but there was one direction in which they could be magnetized with a facility and force greater than in any other. From the appearances I am inclined to refer this to the crystalline condition, but it may be due to an irregular diffusion of iron in the masses of titanium. The crystals were too small for me to make out the point clearly.

scholarly journals Experimental researches in electricity. Twenty-fifth series. On the magnetic and diamagnetic condition of bodies

1851 ◽  
Vol 5 ◽  
pp. 995-997
Keyword(s):  
Physical Condition ◽  
Internal Surface ◽  
The Other ◽  
Magnetic Action ◽  
The One ◽  
Magnetic Poles ◽  
Experimental Researches ◽  
Different Gases ◽  
Insight Into ◽  
Made In

As the author could find no polarity in diamagnetic bodies when under magnetic influence (a result described in the 23rd Series of these Researches), he endeavoured to discover some other physical condition of them, and of magnetic bodies, by which he might obtain an insight into their respective natures, and establish the true place of the magnetic zero; and considering the power with which a magnetic body moves, or tends to move, from weaker to stronger places of action, and that of a diamagnetic body to pass from stronger to weaker places of action, he hoped to obtain some results of condensation with the first class, and of expansion with the second, when they were subjected to very strong magnetic action; the respective bodies being selected from the class of gaseous substances, in which change of volume can be easily produced and measured. In the first place, therefore, a ray of light was passed over the surface of powerful magnetic poles surrounded by different gases, and the place of its source carefully examined by telescopes, micrometers, and other means, to ascertain whether the layer of air in contact with the poles was affected in its refracting force; but though the experiment was made in oxygen, nitrogen, and other gases, not the slightest effect was visible. Resigning this process, therefore, two air-tight chambers were made, in which the magnetic poles formed the chief part of the internal surface of the chamber. The one was formed by bringing the flat ends of the two poles to within 1/60th of an inch of each other, with a frame all round to form the sides; and the other by cutting away the central parts of an iron cylinder so as to give it the form of an hour-glass, and then enclosing that part by an air-tight copper tube. Cocks were attached to these chambers for the introduction and removal of gases, and for the application of gauges, which were able to indicate a change of volume equal to the part of the contents of the chamber. When any given gas was introduced into the chamber, and the latter then placed between the poles of the electro-magnet, any possible alteration of volume would be shown by the gauge as soon as the magnet was rendered active; but whatever gas was employed, or whatever power of magnet used, not the slightest change was produced.

Experimental researches in electricity. Atmospheric magnetism, continued. Twenty-seventh series

1851 ◽  
Vol 5 ◽  
pp. 1000-1001
Keyword(s):  
Electric Current ◽  
Copper Wire ◽  
Average Temperature ◽  
Magnetic Forces ◽  
The North ◽  
The Earth ◽  
Axis Parallel ◽  
The Difference ◽  
Experimental Researches ◽  
Lines Of Force

In order to obtain an experimental representative of the action of the atmosphere when heated above or cooled below the average temperature, the author employed a ring helix of covered copper wire, through which an electric current was passed. The helix was about one inch and a half in diameter, and having the well-known system of magnetic forces, was placed with its magnetic axis parallel to a free needle: when its position was such that a needle within the ring would point with the north end downward, then the effect in deflecting the surrounding lines of force of the earth was considered as like that of a relatively paramagnetic mass of air: and when its position was reversed, its action was representative of that of a heated or relatively diamagnetic mass of air. Bringing this helix into the vicinity of small magnetic needles, suspended either freely, or so as to show declination or inclination, the planes of action or indifference as regards the power of deflecting the lines of force and the needle were observed. When the needle can move only in one plane, there are four quadrants, formed (in the case of the declination needle) by the intersection of the planes of the magnetic equator and meridian. When in these planes there is no deflection at the needle, but when in the quadrants there is, and in opposite directions in the neighbouring quadrants. As the lines of force are held in and by the earth, so these experiments were repeated with a needle in near vicinity to a magnet, and the difference of effect is pointed out: then the extent to which these results are applicable to those of the earth is considered, and their utility in guiding the inquirer.

I. On the rotation of the plane of polarization of light by reflection from the pole of a magnet

1877 ◽  
Vol 25 (171-178) ◽  
pp. 447-450 ◽  
Keyword(s):  
Strong Solution ◽  
Opposite Direction ◽  
Magnetic Force ◽  
Polarized Light ◽  
Transparent Medium ◽  
Positive Current ◽  
Magnetic Action ◽  
Polarization Of Light ◽  
Experimental Researches

At a meeting of the Dublin Scientific Club on Monday the 6th November, Professor Barrett gave the Club an account of Mr. Kerr’s experiments on the rotation of the plane of polarization of a ray of light when reflected from the surface of the end of a magnet, to which additional interest was attached by the reading of a letter from Mr. Kerr to Professor Barrett giving an account of the mode of making and of the last results of his experiments. At the time I proposed trying whether any similar effects would be produced by reflection from the surface of a crystal of quartz cut perpendicularly to the axis, as I was led to think there might be, owing to the similarity of the rotatory polarization of quartz and of substances under magnetic action. Following out that clue, I obtained the following explanation of Mr. Kerr’s experiment, and was enabled, through Professor Barrett’s kindness in helping me to verify my recollections of Mr. Kerr’s letter, to make sure that my theory explains the facts. Faraday has shown, in the nineteenth series of his experimental researches, that a ray of plane-polarized light, when transmitted through any solid (diamagnetic ?) transparent medium under the action of a powerful magnet, has the plane of its polarization rotated in that direction in which a positive current must circulate round the ray in order to produce a magnetic force in the same direction as that which actually exists in the medium. Verdet, however, discovered that in certain ferromagnetic media (as, for instance, a strong solution of perchloride of iron in wood-spirit or ether) the rotation is in the opposite direction to the current which would produce the magnetic force.

scholarly journals XIV. Experimental researches in electricity.—Tenth series

1835 ◽  
Vol 125 ◽  
pp. 263-274
Keyword(s):  
Electric Current ◽  
Royal Society ◽  
The Other ◽  
The One ◽  
Experimental Researches

1119. I have lately had occasion to examine the voltaic trough practically, with a view to improvements in its construction and use; and though I do not pretend that the results have anything like the importance which attaches to the discovery of a new law or principle, I still think they are valuable, and may therefore, if briefly told, and in connexion with former papers, be worthy the approbation of the Royal Society. 16. On an improved form of the Voltaic Battery . 1120. In a simple voltaic circuit (and the same is true of the battery) the chemical forces which, during their activity, give power to the instrument, are generally divided into two portions; the one of these is exerted locally, whilst the other is transferred round the circle (947. 996.); the latter constitutes the electric current of the instru­ment, whilst the former is altogether lost or wasted. The ratio of these two portions of power may be varied to a great extent by the influence of circumstances: thus, in a battery not closed, all the action is local; in one of the ordinary construction, much is in circulation when the extremities are in communication; and in the perfect one, which I have described (1001.), all the chemical power circulates and becomes elec­tricity. By referring to the quantity of zinc dissolved from the plates (865. 1126.), and the quantity of decomposition effected in the volta-electrometer (711. 1126.) or elsewhere, the proportions of the local and transferred actions under any particular circumstances can be ascertained, and the efficacy of the voltaic arrangement, or the waste of chemical power at its zinc plates, be accurately determined.

scholarly journals IX. Experimental researches in electricity.—Thirtieth series

1856 ◽  
Vol 146 ◽  
pp. 159-180 ◽  
Keyword(s):  
Magnetic Field ◽  
Royal Society ◽  
Surrounding Medium ◽  
Electric Currents ◽  
Magnetic Action ◽  
Different Temperatures ◽  
The One ◽  
New Phenomena ◽  
Experimental Researches ◽  
Lines Of Force

3363. Whilst using lines of force as a true, searching, and as yet, never-failing representative of the one form of power possessed by paramagnets, diamagnets, and electric currents,—and whilst endeavouring simultaneously to make the principle of representation a key to new phenomena, and subjecting the principle itself to rigid cross examination,—I have had occasion to examine the action of certain magnetic bodies in different media and at different temperatures; and as the results are true, and must, therefore, be valuable in any view of the cause of magnetic action, I have thought them worthy of presentation to the Royal Society. 3364. When an unmagnetized but magnetic body, placed in a magnetic field, is affected by the forces thrown upon it, and under their action sets , or takes up a definite position, the effect may depend upon its peculiar molecular condition, or upon its relation to the surrounding medium, or upon both conjointly, or upon one or both combined with temperature. Some of each of these conditions have been the objects of my investigations.

scholarly journals On some phenomena and motions of metals under the influence of magnetic force

1851 ◽  
Vol 5 ◽  
pp. 855-856
Keyword(s):  
Electric Current ◽  
Magnetic Force ◽  
Magnetic Forces ◽  
Battery Power ◽  
Gold Silver

In the course of some experiments relative to the principal phenomena of dia-magnetism, the author observed that the nature or direction of the action upon many metals varied with the intensity of the magnetic force, the effects being in accordance with the observations of Professor PIücker; and in pursuing his researches with the view to ascertain how far the magnetic and dia-magnetic forces might be coexistent in the same metal, other phenomena dependent on the power of the magnet presented themselves. On submitting gold, silver, lead, tin, zinc and cadmium to the action of the electromagnet when excited by an electric current of moderate strength, or when the polar terminations of the magnet were at a distance not less than an inch, these metals pointed axially. When the battery power was somewhat increased and the poles brought nearer to each other, instead of the metal being more strongly attracted, it became less sensible to either attraction or repulsion, becoming very sluggish in its motions; but when the magnet was well-excited and the polar terminations brought within a quarter of an inch of each other, most of those metals pointed decidedly equa-torially, and were repelled as dia-magnetics.

scholarly journals Experimental researches in electricity. Twenty-sixth series. On magnetic conducting power and atmospheric magnetism

1851 ◽  
Vol 5 ◽  
pp. 998-1000
Keyword(s):  
Magnetic Field ◽  
Differential Effect ◽  
Magnetic Force ◽  
The Other ◽  
Parallel Lines ◽  
Magnetic Action ◽  
Magnetic Poles ◽  
Experimental Researches ◽  
The Magnetic Field ◽  
Two Bodies

The remarkable results respecting oxygen and nitrogen described in the last Series, and the absence of any change of volume under strong magnetic action, led the author to apply for a time the idea of conducting power to the magnetic phenomena there described, meaning by that phrase the capability which bodies possess of affecting the transmission of the magnetic force without any reference to the process by which that transmission is effected; and assuming that two bodies are at the same time in the magnetic field, and that one displaces the other, he considers the result as a differential effect of their difference in conducting power. If a free portion of space be considered with lines of equal magnetic force passing across it, they will be straight and parallel lines. If a sphere of paramagnetic matter be placed in such a space, they will gather upon and in the sphere, being no longer parallel in their course, nor of equal intensity in every part; or if a sphere of diamagnetic matter replace the former sphere, the lines of force will open out where the sphere is, being again no longer parallel in direction nor uniform in force. When the field of magnetic force is formed between the opposite flat ends of two large magnetic poles, then these are affected, and the globes also, and there are mutual actions; a paramagnetic body, if a little elongated, points axially and tends to go to the iron walls of the field, whilst a similar diamagnetic body points equatorially, and tends to go to the middle of the field. Paramagnetic bodies repel each other, and so also do diamagnetic bodies; but one of each class being taken, they attract one another.

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