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A Result from the NIST Watt Balance and an Analysis of Uncertainties



Richard L. Steiner, David B. Newell, Edwin R. Williams


An improved determination of the ratio of power, measured in terms of the Josephson and quantum Hall effects, and also the meter, kilogram, and second, has been completed. The result is expressed as: W90/W = 1 + (8187) x 10-9. This is an order of magnitude improvement from the last NIST (formerly NBS) determination. The Type A standard relative uncertainty (statistical) is 30nW/W, and the Type B relative standard uncertainty is 82 nW/W. Type B uncertainty components are listed and discussed within the context of experimental procedure descriptions. Improvements for the next version of this experiment, are also mentioned.
IEEE Transactions on Instrumentation and Measurement


electron mass, fundamental constants, Josephson constants, kilogram, mass drift, Planck constant, Watt-SI


Steiner, R. , Newell, D. and Williams, E. (1999), A Result from the NIST Watt Balance and an Analysis of Uncertainties, IEEE Transactions on Instrumentation and Measurement, [online], (Accessed May 30, 2024)


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Created March 31, 1999, Updated October 12, 2021