The relationship between the SI Ohm, the Ohm at NPL, and the quantized Hall resistance

• Published in: IEEE transactions on instrumentation and measurement Vol. IM-36; no. 2; pp. 208 - 213
• Main Authors: Hartland, Anthony, Jones, R. Gareth, Kibble, Bryan P., Legg, David J.
• Format: Journal Article
• Language: English
• Published: IEEE 01.06.1987
• Subjects: Current measurement; Electrical resistance measurement; Measurement uncertainty; Resistance; Resistors; Temperature measurement; Uncertainty
• ISSN: 0018-9456; 1557-9662
• DOI: 10.1109/TIM.1987.6312670

New measurements relating the quantized Hall resistance R H (= h/ie 2 ), International System (SI) Ohm (Ω SI ), and the National Physical Laboratory maintained ohm (Ω NPL ) have now been completed at NPL in the U.K. with improvements and simplifications in the cryogenic current comparator measurements and 1000-Ω dc resistance measurements. From the measurements over the past four years the relationship between Ω NPL and Ω SI can be described by the equation Ω NPL − Ω SI = −1.049(0.020) − 0.0478(0.0074)[t − 1986.0] μΩ in which t is measured in years. For the previous two years the equivalent relationship between R H and Ω NPL is R H = 25 812.8(1 + 1.452(0.038) × 10 −6 + 0.0694(0.0772) · [t − 1986.0] × 10 −6 ) Ω NPL in which the uncertainties (in parentheses) are one-standard-deviation (1σ) random uncertainties of the least squares fit to the data. Combining the most recent measurements of R H and Ω SI , using a more direct method of measurement R H = 25 812.8106(17) Ω SI in which the relative combined uncertainty is 0.067 × 10 −6 .