Electric-currents Sentence Examples
The coolness of his touch turned to gentle electric currents that worked their paths through her skull.
He also made important contributions to the mathematical theory of electrodynamics, and in papers published in 1845 and 1847 established mathematically the laws of the induction of electric currents.
This, with proper apparatus for originating electric currents at one end and for discovering the effects produced by them at the other end, constitutes an electric telegraph.
He found, as others have dune, that if a battery, dynamo or induction coil has its terminals connected to the earth at two distant places, a system of electric currents flows between these points through the crust of the earth.
Direct reading equidivisional movable coil ammeters can be made in various portable forms, and are very much employed as laboratory instruments and also as ammeters for the measurement of large electric currents in electric generating stations.Advertisement
Immediately on its discovery intense interest was aroused in the new invention, and the chemical effects of electric currents were speedily detected.
A good many years later he was entrusted by the committee of the British Association on standards of electric resist ance with the task of deducing the mechanical equivalent of heat from the thermal effects of electric currents.
The meter is made up also in a form suitable for use with two or three fixed electric currents.
It is true that the theory of vortex rings in hydrodynamics is of a simpler type; but electric currents cannot be likened to permanent vortex rings, because their circuits can be broken and the element of cyclic steadiness on which the simplicity depends is thereby destroyed.
One of the most important industrial enterprises in the city is the electric plant belonging to the Rio de Janeiro Light and Power Company, which supplies electric currents for public and private lighting, and power for the tramways and many industries.Advertisement
We must now go on to the crowning discovery of the induction of electric currents.
The case of electro-magnetic forces between two conductors carrying electric currents affords an example of a statement of motion in terms of force of a highly artificial kind.
The behaviour of the needle, as Paulsen points out, is exactly what it should be if the space occupied by the auroral curtain were traversed by electric currents directed upwards from the ground.
Birkeland (19), who has made a special study of magnetic disturbances in the Arctic, proceeding on the hypothesis that they arise from electric currents in the atmosphere, and who has thence attempted to deduce the position and intensity of these currents, asserts that whilst in the case of many storms the data were insufficient, when it was possible to fix the position of the mean line of flow of the hypothetical current relatively to an auroral arc, he invariably found the directions coincident or nearly so.
In the marsupials it is more evident, and its excitation by electric currents evokes movements in the musculature of the crossed side of the body.Advertisement
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.
Arago's previous investigations in the new science of electromagnetism, and crowned that labour by the announcement of his great discovery of the dynamical action between conductors conveying the electric currents.
Ampere in this paper gave an account of his discovery that conductors conveying electric currents exercise a mutual attraction or repulsion on one another, currents flowing in the same direction in parallel conductors attracting, and those in opposite directions repelling.
Ampere had already previously shown that a spiral conductor or solenoid when traversed by an electric current possesses magnetic polarity, and that two such solenoids act upon one another when traversed by electric currents as if they were magnets.
These advances all centre round his supreme discovery of the induction of electric currents.Advertisement
Kirchhoff determined experimentally in a certain case the absolute value of the current induced by one circuit in another, and in the same year Erik Edland (1819-1888) made a series of careful experiments on the induction of electric currents which further established received theories.
By this simple device he provided a means of measuring small electric currents far in advance of anything yet accomplished, and this instrument proved not only most useful in pure scientific researches, but at the same time was of the utmost value in connexion with submarine telegraphy.
The fundamental fact connecting electric currents and magnetic fields is that the line integral of magnetic force taken once round a conductor conveying an electric current is equal to 4 7r-times the surface integral of the current density, or to 4 7r-times the total current flowing through the closed line round which the integral is taken (see Electrokinetics).
In 1840 he showed that when an electric current was produced by means of a dynamo-magneto-electric machine the heat generated in the conductor, when no external work was done by the current, was the same as if the energy employed in producing the current had been converted into heat by friction, thus showing that electric currents conform to the principle of the conservation of energy, since energy can neither be created nor destroyed by them.
The heat makes itself evident by raising the temperature and therefore elongating the wire, whilst the magnetic field creates mechanical forces which act on pieces of iron or other conductors conveying electric currents when placed in proximity to the conductor in question.Advertisement
Fleming, Magnets and Electric Currents (London, 1898); C. Maurain, Le magnetisme du fer (Paris, 1899; a lucid summary of the principal facts and laws, with special regard to their practical application); Rapports presentes au Congrks international de physique, vol.
Leyden jars are now much employed for the production of the high frequency electric currents used in wireless telegraphy (see Telegraphy, Wireless).