A MAGNETIC CURVE TRACER 



25 



deflection produced the rekition between the quantity of electricity 

 passing through the fluxmeter and its deflection can he determined. 

 From this relation and other known constants the change in induction 

 of a magnetic specimen producing a given deflection ma\' he calculated. 

 This calibration may be done in the following manner: Let the 



Fig. 7 — Hysteresis loop of pcrniinvar, sliowing the "wasp waisted" loop. 



magnetic specimen be remo\ed, Ri and Ri-, be set on infinite resistance, 

 the magnetizing coil F be shorted, and a change in the held current 

 made which will give a convenient deflection on the drum, as shown in 

 Fig. 8. 



Fig. 8 — Line taken for calibrating the apparatus. 



Let Im = instantaneous primary current, 

 to = instantaneous secondary current, 

 ^2 = resistance of secondary circuit, 

 AI = mutual inductance of M, 

 L2 = self inductance of secondary circuit. 



