Alternate Current Measurement . ntmeasurements. When suitable scales are chosen the curve must also be suchthat the ordinate is equal to AKi when the abscissa is equal to BKi in fig. value of Kc obtained will be inversely proportional to the square of thecurrent frequency used, since the ampere turns BA needed to produce a givenreactive voltage U will vary inversely as the frequency, while the ampere 340 Dr. W. E. Sumpner. [Jan. 21r turns BKi due to a capacity Ki will be directly proportional to the a similar reason the capacity needed will be inversely proportional tothe
Alternate Current Measurement . ntmeasurements. When suitable scales are chosen the curve must also be suchthat the ordinate is equal to AKi when the abscissa is equal to BKi in fig. value of Kc obtained will be inversely proportional to the square of thecurrent frequency used, since the ampere turns BA needed to produce a givenreactive voltage U will vary inversely as the frequency, while the ampere 340 Dr. W. E. Sumpner. [Jan. 21r turns BKi due to a capacity Ki will be directly proportional to the a similar reason the capacity needed will be inversely proportional tothe square of the number of turns used on the secondary winding. All thesepoints have been fully verified by actual tests. The results given below in Table I and fig. 9 are taken from a set of testsmade on an electromagnet provided with a moving coil, and connected up asa voltmeter of the magnetostatic type previously described. The connec-tions of the coils are shown diagrammatically in fig. 8. The field coil 5o£. 500 £. 500 £.. Fig. 8. consisted of two coils of 500 turns each, the two coils being twin wound1round the core so as to ensure that each coil enclosed the same These*coils were permanently connected in series. The moving coil, , was*connected to the terminals of one of the windings of 500 turns through a>condenser k of 0*5 microfarad capacity. The core of the magnet was woundwith an extra coil of 50 turns. The pointer was found to defteet to a certainmark on the scale when 80 volts were applied to 1000 turns (or 40 volts to*500 turns). The deflection for a given voltage was the same for anyordinary frequency of the voltage used for the test. This deflection wasutilised in the tests to adjust the reactive voltage of the core to a constantvalue. Experiments were then made by passing an alternating current ofA amperes through the 50-turn coil. The current frequency was kept;constant at 80 cycles per second, and A was adjusted by means of suitable--resistance
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