The design, contruction, and use of resistors of calculable reactance

The design, construction, and use of two-termInal resistors of calculabel reactance, covering the range 100¿10 000 ohms are described. The resistors form a series of primary standards suitable for the measurement of residual inductance and are of two forms; those in the range 100¿1 000 ohms consist of a single straight wire concentrically mounted withing a return conductor, while those in the range 1000¿10000 ohms consist of single-layer solenoids similarly mounted. The former are suitable for measurements up to a frequency of 10000 cycles per sec. and the latter for measurements up to 3000 or 4000 cycles per sec. The inductances and capacitances of the standards are calculated as far as possible from their dimensions, although certain of the cpacitances involved were measured directly. The variation of reactance with frequency is discussed and experimental confirmation of theoretical predictions is given. Comparison measurements between the standards have been carried out using simple bridge methods, and the general consistency of the results shows that, using these standards and methods, the phase angle of any resistor in the range under discussion can be determined with an accuracy of 6 × 10¿6 radian at 1000 cycles per sec. even when bridge ratios as high as 10:1 are involved. As an additional check, the values of ractance were determined in terms of the constants of high-frequency self-inductance standards, and the claculated and observed results were found to show the same consistency.