. The Bell System technical journal. Telecommunication; Electric engineering; Communication; Electronics; Science; Technology. MAGNET STEELS AND PERMANENT MAGNETS 387 Following the permeameter measurements, each bar was magne- tized as a straight bar magnet in an air core solenoid. Field strengths of over 1,000 oersteds were applied to each bar. Upon removal from the solenoid the flux density at the middle of the bar was measured by means of a search coil and the Grassot fluxmeter with lamp and scale. It is the flux density measured in this way that is referred to in this discussion as the rem
. The Bell System technical journal. Telecommunication; Electric engineering; Communication; Electronics; Science; Technology. MAGNET STEELS AND PERMANENT MAGNETS 387 Following the permeameter measurements, each bar was magne- tized as a straight bar magnet in an air core solenoid. Field strengths of over 1,000 oersteds were applied to each bar. Upon removal from the solenoid the flux density at the middle of the bar was measured by means of a search coil and the Grassot fluxmeter with lamp and scale. It is the flux density measured in this way that is referred to in this discussion as the remanence of a magnet, or Brem- After the measurements at 12-in. lengths were completed, each bar was cut in succession to 10, 8, 6, 4, and 2-in. lengths by removing 1 inch of material from each end except that in the case of some of the bars of larger cross-section the lengths of 10, 6, and 2 inches were omitted. Remanence measurements were made at each of the above lengths. IIO-VOLT DC SUPPLY AMMETER GRASSOT FLUXMETER B-COIL OF J-PERMEAMETER MAGNETIZING COIL OF J-PERMEAMETER PM mutual INDUCTANCE PRIMARY S^, MUTUAL INDUCTANCE SECONDARY L A G Bj Mj. Fig. 3—Control circuit of the Babbitt perrneameter. Note that the connections are those of a simple ring test. The bars were remagnetized for each new measurement of Brem- The foregoing experiments made available for analysis a wide range of values of the associated variables , Br, H,, length L, and cross- sectional area A. Analysis of Data. The values of remanence versus length for a number of the straight bar magnets are plotted in Fig. 4 to show the range of values existing in different bar magnets of the same length, when fully magnetized. The differences in Brem for a particular length of bar are due to the differences in Br, He, and cross-section of the various samples. The chief characteristic that the curves of Fig. 4 have in common is a resemblance in shape to a normal induction curve and an asymptotic approach to limiti
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