The Measurement of Magnetic Hysteresis . aiven in the table. ?0 XXa » » » • « V 10 1 15*72 j 26*64 37*4 ? m . 1*25 1-98 1 2*94 3-32 •64(11^-6*2)^ . 1*25 1*97 \ 2*90 3*57 Thus, approximately, W = *64(Ho-~- 6-2)%. This expression would naturally fail to represent facts when Hq < 6*2. The value of W for zero stress, recorded in § 54, is given closely over the wholerange by W = •57H^oBq —1800, § 67. We now take the experiments on the effect of tension upon a soft iron wiredescribed in § 52. The curves connecting W with Bq are shown in fig. 17 along withthe W — Bq curve for zero stress. Each of
The Measurement of Magnetic Hysteresis . aiven in the table. ?0 XXa » » » • « V 10 1 15*72 j 26*64 37*4 ? m . 1*25 1-98 1 2*94 3-32 •64(11^-6*2)^ . 1*25 1*97 \ 2*90 3*57 Thus, approximately, W = *64(Ho-~- 6-2)%. This expression would naturally fail to represent facts when Hq < 6*2. The value of W for zero stress, recorded in § 54, is given closely over the wholerange by W = •57H^oBq —1800, § 67. We now take the experiments on the effect of tension upon a soft iron wiredescribed in § 52. The curves connecting W with Bq are shown in fig. 17 along withthe W — Bq curve for zero stress. Each of the curves, which shew the effects of stress,is again made up of a straight part and a hook, the straight parts radiating from thepoint Bq = —600, W = —950. For the slope of the lines we have ON THE MEASUEEMENT OP MAGNETIC HYSTEEESIS. 9i a m 353^0 • • * 4-524 11-00 16-24 •741 1-20 1 1-36 •750 1-17 1-42 i so that the straight parts are given by W = -35311% (Bq + 600) - 950. 6000 160GO 14000 12000 lOOOO. 8000 10000 12000 14000 Fig. 17. The curves just described differ in two important particulars from the curves fortorsion in fig. 10. In the case of torsion the straight parts of the curves correspond tolarge stresses and the hooks to small stresses, but in the case of tension the straightparts correspond to small stresses and the hooks to large stresses; the hook is more-over much more developed in the curves for tension than in the curves for second point of difference is that the tension curves lie to the right of theW — Bq curve for zero stress whereas the torsion curves lie to the left. N 2 92 MESSES. G. F. C. SEARLE AND T. G. BEDFOED § 68. So far the strains have been practically within the elastic limit. We nowexamine some cases in which this limit was much exceeded. In the W—Bq curve, plotted from the experiments described in § 60, the pointsappear to be irregularly placed till the torsion wheel has made about eight revolution
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