The absolute measurement of inductance . tted curve. Nevertheless, they madean appreciable error in the value of the correction factor sought, andhence it was desirable to eliminate all such residual errors. The harmonics of the current are readily computed from those ofthe electromotive force which produces the current, and since in aninductive circuit the latter are larger than the former, the errors ofthe curve and of the analysis are divided down in the calculation anda more accurate result may therefore be obtained. 134 BULLETIN OF THE BUBEAU OF STANDARDS. [vol. l, no. 2. Thus, for the th
The absolute measurement of inductance . tted curve. Nevertheless, they madean appreciable error in the value of the correction factor sought, andhence it was desirable to eliminate all such residual errors. The harmonics of the current are readily computed from those ofthe electromotive force which produces the current, and since in aninductive circuit the latter are larger than the former, the errors ofthe curve and of the analysis are divided down in the calculation anda more accurate result may therefore be obtained. 134 BULLETIN OF THE BUBEAU OF STANDARDS. [vol. l, no. 2. Thus, for the third harmonic the impedance is >/{B + rf + 9p2Z2 instead of <S(B + r)* +p*Z* and, in a particular case, its numerical value is as follows: r = = = p = 2?r n = 2 ttX = , Imp, = x/()2 + ()2 =, = x/()2 +9()2 rF , = v/()2 +25()2 = , = v/()2 + 49()2 - Hence, f^ = |®= f^ = 7m/?! /ra^ 7m^x. Fig. 4.—Current in condenser due to electromotive force of fig. 3. These quotients show how much smaller relatively the third, fifth,and seventh harmonics are in the inductive current curve than in theelectromotive force curve. Therefore the third, fifth, and seventhharmonics in the current curve may be found by dividing the corre-sponding harmonics in the electromotive force curve by the , , , respectively. Small errors due to the curve itself orto the analysis are thus divided by these factors, and the values of theharmonics found are therefore more accurate and more consistent thanif determined directly by analyzing the current curve. ROSA,GROYER ] ABSOLUTE MEASUREMENT OF INDUCTANCE. 135 This process may indeed be carried another step by placing a con-denser in parallel with the circuit AB (7, so that the alternating currentflowing into it will be due to the same electromotive force that causes
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