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I.—The Shift of the Neutral Points due to Variation of the Intensity of Mechanical Vibrations or Electric Oscillations superposed upon Cyclic Magnetisation in Iron
Published online by Cambridge University Press: 15 September 2014
Extract
When mechanical vibrations or electric oscillations are superposed at all points of a normal hysteresis loop, the induction at the cyclic extremes is increased, the residual magnetisation decreased, and those differences of magnetic condition to which hysteresis gives rise lessened. The curves delineating these changes form a continuous loop, and neutral points occur where vibrations superposed upon decreasing cyclic field produce no induction change whatever.
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- Copyright © Royal Society of Edinburgh 1909
References
page 2 note * “The Superposition of Mechanical Vibrations (Electric Oscillations) upon Magnetism, and conversely, in Iron, Steel, and Nickel,” Trans. R.S.E., vol. xlv., part ii., p. 510. Phil. Mag., Oct. 1907. Electrician, July 5, 1907Google Scholar.
page 2 note † “Les Détecteurs magnétiques et l'action des Oscillations électriques sur l'aimantation,” Journal de Physique, Janvier 1907Google Scholar.
page 2 note ‡ Proceedings of the Physical Society of London, vol. xx. Phil. Mag., August 1906Google Scholar.
page 2 note § Note presented at the Meeting of the American Association for the Advancement of Science, by G. F. Stradling. (Reports have not been received by the R.S.E. for several years.)
page 15 note * This was found to be absolutely necessary. Without the earth connection, the spot of light moved over a large part of the scale, more especially just before the passage of the spark; with the earth connection, a sharp deflection was obtained on the passage of the spark, in the vast majority of cases from a steady zero position.
page 26 note * “presque nulle”; see p. 2.
page 36 note * This compounding of the irreversible with the reversible effects may very easily be lost sight of. The following appears to be worth further consideration. Professor Rutherford, in his determination of the damping of oscillations by the magnetic method, assumes that if the initial phase of the oscillation train be such as to increase the magnetisation of the bundle of steel needles, it will produce no magnetic effect, because these have been magnetised to saturation. That is to say, as the initial phase increases to a maximum the magnetisation will increase, and as the initial phase falls to zero the decrease of magnetisation will not exceed the previous increment. But the irreversible (vibrational) effect opposes the increase and assists the decrease, hence the residual magnetisation may fall below its original value. The proof as stated would therefore appear to be incomplete.
page 36 note † “The Effect of Load and Vibrations upon Magnetism in Nickel,” pp. 38–56. Read in conjunction with this paper.
page 36 note 1 “On a Magnetic Detector of Electric Waves, and some of its Applications,” Phil, Trans. Roy. Soc., London, A., 1897, vol. clxxxix., p. 1Google Scholar.
page 37 note * In a later communication than that already referred to (p. 2), Professor Maurain states that “la courbe normale dépend un peu du l'amplitude des cycles de torsion.” See “Sur l'action de la torsion sur l'aimantation,” Journal de Physique, May 1907Google Scholar. In other words, the vibrational neutral points shift with the intensity of the torsional disturbance.