Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Coil motion effects in watt balances: a theoretical check

Published

Author(s)

Stephan Schlamminger, Shisong Li, Darine El Haddad, Frank C. Seifert, Leon S. Chao, Jon R. Pratt

Abstract

A watt balance is a precision apparatus for the measurement of the Planck constant that has been proposed as a primary method for realizing the unit of mass in a revised International System of Units. In contrast to an ampere balance, which was historically used to realize the unit of current in terms of the kilogram, the watt balance relates electrical and mechanical units through a virtual power measurement and has far greater precision. However, because the virtual power measurement requires the execution of a prescribed motion of a coil in a fixed magnetic field, systematic errors introduced by horizontal and rotational deviations of the coil from its prescribed path will compromise the accuracy. We model these potential errors using an analysis that accounts for the fringing field in the magnet, creating a framework for assessing the impact of this class of errors on the uncertainty of watt balance results.
Citation
Metrologia

Keywords

fundamental electrical measurements, watt balance, Planck constant, SI units, mass metrology, revised SI

Citation

Schlamminger, S. , Li, S. , El, D. , Seifert, F. , Chao, L. and Pratt, J. (2016), Coil motion effects in watt balances: a theoretical check, Metrologia, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=919636 (Accessed August 10, 2022)
Created February 10, 2016, Updated October 8, 2019