Measuring 10 gram masses in terms of electrical quantities using a LEGO-based Kibble balance

Published

September 1, 2016

Author(s)

Leon S. Chao, Stephan Schlamminger

Abstract

In 2018, the International System of Units (SI) is expected to undergo a complete redefinition. This redefinition presents a paradigm shift where the present SI, based on seven fundamental units, will evolve into a system based on seven fundamental constants. More specifically, the unit of mass, the kilogram, will no longer be defined by an artifact standard, but rather be derived from a fixed value of the Planck constant h. One possible means to realize the unit of mass from h is provided by the watt balance (or Kibble balance), invented in 1975 by Dr. Bryan Kibble (1938-2016). Since the advent of his concept, many national metrology institutes around the world have worked toward developing watt balances capable of realizing a kilogram mass with relative uncertainties of a few parts in 10^8. At the National Institute of Standards and Technology (NIST), located in the USA, we have developed a high-precision, full-sized watt balance as well as a fun, tabletop watt balance constructed from LEGO bricks capable of measuring gram-sized masses with a relative uncertainty of 1%. This article presents the design, construction, and performance of the LEGO watt balance and its ability to measure a small mass.

Citation

Lab World Magazine

Volume

06

Pub Type

Journals

Download Paper

Local Download

Citation

Chao, L. and Schlamminger, S. (2016), Measuring 10 gram masses in terms of electrical quantities using a LEGO-based Kibble balance, Lab World Magazine, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=921426 (Accessed October 16, 2025)