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PUBLICATIONS

An Accurate Measurement of Planck's Constant

Published

Author(s)

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

Abstract

Using a moving coil watt balance, electric power measured in terms of the Josephson and quantum Hall effects is compared with mechanical power measured in terms of the meter, kilogram and second, we find the Planck constant h = 6.62606891(58) x 10-34 Js. The quoted standard uncertainty ( 1 standard deviation estimate) corresponds to (8.7 x 10-8) h. Comparing this measurement places an upper limit of 2 x 10-8 / year on the drift rate of the SI unit of mass, the Kilogram.
Citation
Physical Review Letters
Pub Type
Journals

Keywords

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

Citation

Williams, E. , Steiner, R. and Newell, D. (1998), An Accurate Measurement of Planck's Constant, Physical Review Letters (Accessed May 9, 2025)

Issues

If you have any questions about this publication or are having problems accessing it, please contact reflib@nist.gov.

Created June 30, 1998, Updated October 12, 2021