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Paper, 'On the production of transient electric currents in iron and steel conductors by twisting them when magnetised, or by magnetising them when twisted' by J A [James Alfred] Ewing

Reference number: PP/4/7

Date: 1882

Description

Ewing writes: 'A chance observation, made in the summer of 1881, drew my attention to the fact that when the ends of an iron wire are connected to the terminals of a galvanometer, a transient current will be observed if the wire he suddenly magnetised while it is held in a state of torsion, or suddenly twisted whilst in a state of longitudinal magnetisation. Further inquiry showed that these currents are satisfactorily explainable by reference to the results of more direct observations which have been made on the effects of stress on magnetism. They present, however, certain features of interest, and the examination of them, of which a condensed account is given below, may form a useful supplement to any direct investigation of the effects of stress on magnetic susceptibility and residual magnetism. 2. A straight, moderately soft, well-annealed iron wire, 1 millim. in diameter and 34 centims. long, was placed horizontally in an E. W. position, with one end securely fixed and the other held by a twisting arm, by which any desired amount of torsion might be applied. The twisting arm was provided with a pointer, which travelled over a graduated circular dial. The ends of the wire were connected by long leading wires to a Thomson’s mirror galvanometer of 0·25 ohm resistance, with a heavy mirror, which made it fairly suitable for ballistic work. Round the iron wire was a magnetising solenoid of 660 turns, 31 centims. long, in two layers, wound so as to have no longitudinal component parallel to the wire. In circuit with the solenoid was a single large Daniell’s cell and a reversing key. The resistance of this circuit was 1·36 ohms and, if we assume the electromotive force of the cell to have been 1 volt, the magnetising force was therefore 4π x 660/31 x 1 x 108/1·36 x 109 = 20 c. g. s. units very nearly.'

Annotations in pencil and ink. Includes four pages of diagrams of experimental apparatus and results.

Subject: Electromagnetism

Received 21 October 1882. Read 15 November 1883.

A version of this paper was published in volume 36 of the Proceedings of the Royal Society as 'On the production of transient electric currents in iron and steel conductors by twisting them when magnetised, or by magnetising them when twisted'.

Reference number
PP/4/7
Earliest possible date
1882
Physical description
Ink and graphite pencil on paper
Page extent
31 pages
Format
Manuscript
Diagram

Creator name

James Alfred Ewing

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Citation

James Alfred Ewing, Paper, 'On the production of transient electric currents in iron and steel conductors by twisting them when magnetised, or by magnetising them when twisted' by J A [James Alfred] Ewing, 1882, PP/4/7, The Royal Society Archives, London, https://makingscience.royalsociety.org/items/pp_4_7/paper-on-the-production-of-transient-electric-currents-in-iron-and-steel-conductors-by-twisting-them-when-magnetised-or-by-magnetising-them-when-twisted-by-j-a-james-alfred-ewing, accessed on 04 November 2024

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  • Proceedings Papers

    Dates: 1882 - 1894

    The archival collection known as 'Proceedings Papers' is comprised of manuscripts and occasional proofs of scientific papers sent to the Royal Society which were read before meetings of Fellows and printed in full in the Proceedings of the Royal Society.

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