The convection of a medium thus polarized involves electric disturbance, and therefore must contribute to the true electric current; the determination of this constituent of the current is the most delicate point in the investigation.
This pressed amber yields brilliant interference colours in polarized light.
(5), of polarized light are executed in a direction perpendicular to the plane of polarization.
The 19th series (1845) contains an account of his brilliant discovery of the rotation of the plane of polarized light by transparent dielectrics placed in a magnetic field, a relation which established for the first time a practical connexion between the phenomena of electricity and light.
Conceive a beam of plane polarized light to move among a number of particles, all small compared with any of the wavelengths.
The crystals are feebly doubly refracting, and in polarized light exhibit a banded structure parallel to the cube faces.
The different behaviour of these two acids to a ray of polarized light was subsequently observed by J.
One possessed the power of turning the plane of the polarized ray to the right; the other possessed no rotary power.
The proof of this statement rests on the fact that if the hydrogen atoms were not co-planar, then substitution derivatives (the substituting groups not containing asymmetric carbon atoms) should exist in enantiomorphic forms, differing in crystal form and in their action on polarized light; such optical antipodes have, however, not yet been separated.
In polarized light they show a weak grey colour with a black cross, the arms of which are parallel to the cobwebs in the eyepiece of the microscope and remain stationary when the section is rotated.
When heated to above 200 it turns brown and produces caramel, a substance possessing a bitter taste, and used, in its aqueous solution or otherwise, under various trade names, for colouring confectionery, spirits, &c. The specific rotation of the plane of polarized light by glucose solutions is characteristic. The specific rotation of a freshly prepared solution is 105°, but this value gradually diminishes to 52.5°, 24 hours sufficing for the transition in the cold, and a few minutes when the solution is boiled.
A part of one surface of the plate may be silvered, so that the polarized ray, after having once traversed the glass, is reflected back again; the rotation is thus doubled, and moreover, the arrangement is, for certain experiments, more convenient than the other.
The existence of internal strains in glass can be readil y recognized by examination in polarized light, any signs of double refraction indicating the existence of strain.
A dielectric substance is electrically polarized by a field of electric force, the atomic poles being made up of the displaced positive and negative intrinsic charges in the atom: the polarization per unit volume (f',g',h') may be defined on the analogy of magnetism, and d/dt(f',g',h') thus constitutes true electric current of polarization, i.e.
For the simplest case of polarized waves travelling parallel to the axis of x, with the magnetic oscillation y along z and the electric oscillation Q along y, all the quantities are functions of x and t alone; the total current is along y and given with respect to our moving axes by __ (d_ d Q+vy d K-1 Q, dt dx) 47rc 2 + dt (4?rc 2) ' also the circuital relations here reduce to _ dydQ _dy _ dx 47rv ' _ dt ' d 2 Q dv dx 2 -417t giving, on substitution for v, d 2 Q d 2 Q d2Q (c2-v2)(7372 = K dt 2 2u dxdt ' For a simple wave-train, Q varies as sin m(x-Vt), leading on substitution to the velocity of propagation V relative to the moving material, by means of the equation KV 2 + 2 uV = c 2 v2; this gives, to the first order of v/c, V = c/K i - v/K, which is in accordance with Fresnel's law.
In 1841 he found that he required rest, and it was not till 1845 that he entered on his second great period of research, in which he discovered the effect of magnetism on polarized light, and the phenomena of diamagnetism.
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.
P. 362) gives the following note from his laboratory book on the 10th of September 1822: "Polarized a ray of lamplight by reflection, and endeavoured to ascertain whether any depolarizing action (was) exerted on it by water placed between the poles of a voltaic battery in a glass cistern; one Wollaston's trough used; the fluids decomposed were pure water, weak solution of sulphate of soda, and strong sulphuric acid; none of them had any effect on the polarized light, either when out of or in the voltaic circuit, so that no particular arrangement of particles could be ascertained in this way."
P. 362) gives the following note from his laboratory book on the 10th of September 1822: "Polarized a ray of lamplight by reflection, and endeavoured to ascertain whether any depolarizing action (was) exerted on it by water placed between the poles of a voltaic battery in a glass cistern; one Wollaston's trough used; the fluids decomposed were pure water, weak solution of sulphate of soda, and strong sulphuric acid; none of them had any effect on the polarized light, either when out of or in the voltaic circuit, so that no particular arrangement of particles could be ascertained in this way."
"I do not think, therefore, that decomposing solutions or substances will be found to have (as a consequence of decomposition or arrangement for the time) any effect on the polarized ray.
He began to work on the 30th of August 1845 on polarized light passing through electrolytes.
It gave no effects when the same magnetic poles or the contrary poles were on opposite sides (as respects the course of the polarized ray), nor when the same poles were on the same side either with the constant or intermitting current.
But when contrary magnetic poles were on the same side there was an effect produced on the polarized ray, and thus magnetic force and light were proved to have relations to each other.
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.
John Kerr (1824-1907) discovered that a similar effect was produced when plane polarized light was reflected from the pole of a powerful magnet (Phil.
Laevo-tartaric acid is identical in its chemical and in most of its physical properties with the dextro-acid, differing chiefly in its action on polarized light, the plane of polarization being rotated to the left.
The optic figure seen in convergent polarized light through a section cut parallel to the plane of symmetry of a borax crystal is symmetrical only with respect to the central point.
Early in 1831 he arranged a small office-bell to be tapped by the polarized armature of an "intensity" magnet, whose coil was in continuation of a mile of insulated copper wire, suspended about one of the rooms of his academy.
A ray of plane-polarized light traversing a right-handed crystal of quartz in the direction of the triad axis has its plane of polarization rotated to the right, while a left-handed crystal rotates it to the left.
Of the interference of polarized rays.
Circularly polarized light he obtained by means of a rhomb of glass, known as "Fresnel's rhomb," having obtuse angles of 126°, and acute angles of 54°.
It rotates the plane of polarized light both to right and left in varying degrees according to its sources, the American product being dextrorotatory and the French laevorotatory.
This term has been retained and the ordinary stream is said to be plane polarized in the principal plane of the face of entry into the rhomb, and the extraordinary stream to be plane polarized in the perpendicular plane.
Thus in accordance with the definition, it is polarized in the plane of incidence.
Further, if polarized light fall at the polarizing angle on a reflecting surface, the intensity of the reflected stream depends upon the azimuth of the plane of incidence, being proportional to the square of the cosine of the angle between this plane and the plane of the polarization.
At angles other than the polarizing angle common light gives a reflected stream .that behaves as a mixture of common light with light polarized in the plane of incidence, and is accordingly said to be partially polarized in that plane.
The refracted light, whatever be the angle of incidence, is found to be partially polarized in a plane perpendicular to the plane of incidence, and D.
Arago showed that at all angles of incidence the reflected and refracted streams contain equal quantities of polarized light.
It follows then that if a stream of light be incident at the polarizing angle on a pile of parallel transparent plates of the same nature, each surface in turn will be met by the light at the polarizing angle and will give rise to a reflected portion polarized in the plane of incidence.
Hence the total reflected light will be polarized in this plane and will of necessity have a greater intensity than that produced by a single surface.
In order to isolate a polarized pencil of rays with a rhomb of Iceland spar, it is necessary to have a crystal of such a thickness that the emergent streams are separated, so that one may be stopped by a screen.
The polarizing action of such crystals is due to the unequal absorption that they exert on polarized streams. Thus a plate of tourmaline of from I mm.
In thickness with its faces perpendicular to the optic axis is nearly opaque to light falling normally upon it, and a plate of this thickness parallel to the axis permits of the passage of a single stream polarized in a plane perpendicular to the principal section.
Such a plate acts in the same way on polarized light, stopping it or allowing it to pass, according as the plane of polarization is parallel or perpendicular to the principal section.
Eisenlohr and others, with the view of determining the direction of the vibrations in polarized light (vide infra), but the results have not been consistent, and H.
The Siemens polarized relay, shown in fig.
- Post Office Polarized Relay.
Currents; the former is polarized and responds to reversals of current, while the latter is non-polarized and responds only to the increased current from K2 irrespective of the direction of that current.
The function of the " combiner " in each receiving instrument is so to group the received combination of positive and negative currents that they operate polarized relays in such a manner that the position of the tongues corresponds with the operation of the levers on the transmitter.
Porphyritic crystals often contract less than the surrounding glass, which accordingly becomes strained, and in polarized light may show a weak double refraction in a limited area surrounding the crystal.
While it cannot be said that the full significance of this very definite phenomenon, consisting of the splitting of the spectral line into a number of polarized components, has yet been made out, a wide field of correlation with optical theory, especially in the neighbourhood of absorption bands, has been developed by Zeeman himself, by A.
For a long time Faraday's observation on the rotation of the plane of polarized light by heavy glass in a 1 H.
This has come about as we have left a polarized world behind us and the importance of military alliances has fallen.
