. The London, Edinburgh and Dublin philosophical magazine and journal of science. d is once morereversed the induction becomes -f Bx ; that is, after thedouble reversal the point A is once more reached. Let nowthe field be gradually increased from +HX to + H2, and theinduction in the specimen will follow the curve from A to after arriving at the point B the field is changed from+ H2 to — H2, the induction changes from +B2 to —Bo ;the kick of the galvanometer is therefore proportionalto 2B2. Following this procedure the complete curve maybe traced out. 8 Dr. J. G. Gray and Mr. A. D. Ross I
. The London, Edinburgh and Dublin philosophical magazine and journal of science. d is once morereversed the induction becomes -f Bx ; that is, after thedouble reversal the point A is once more reached. Let nowthe field be gradually increased from +HX to + H2, and theinduction in the specimen will follow the curve from A to after arriving at the point B the field is changed from+ H2 to — H2, the induction changes from +B2 to —Bo ;the kick of the galvanometer is therefore proportionalto 2B2. Following this procedure the complete curve maybe traced out. 8 Dr. J. G. Gray and Mr. A. D. Ross It seems necessary to add that this only holds for a seriesof fields which are in ascending magnitude, and it is essentialthat the specimen be initially neutral. For the method toyield accurate results the hysteresis loop must be not onlyclosed but symmetrical. If, however, the neutral conditionof the specimen has been interfered with by magnetic orthermal operations, the method is not applicable. This willbe apparent from fig. 3, which is intended to show the results obtained on applying the method to the examination of aspecimen which had been exposed to thermal treatment. Onestablishing the field -fHi the induction became +Bj ; onreversing the field the induction became -r-B2, and B2 differswidely from Bj. The change of induction is B3+B2, andthe kick of the galvanometer is proportional to this change,and hence proportional neither to 2B} nor to 2B2. Themethod of reversals is therefore not applicable unless thespecimen is in the strictly cyclic condition. On once morereversing the field and increasing it to -f H2, the inductionfollowed the curve ADC. If the field +H2 had beenapplied in the first place, a widely different value of theinduction would have been obtained. TJius the magneti-zation curve yielded by this method, when applied to aspecimen in the condition brought about by thermal treatment,depends largely upon the procedure. Table II. shows the results obt
Size: 1853px × 1349px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1840, booksubjectscience, bookyear1840
