Prototype of a Pendulum for Deriving the Kilogram From Electrical Quantities

Several methods have been developed to connect electrical quantities to mechanical quantities. For the same purpose and for the measurement of Planck's constant, a new method based on a pendulum interacting with an electric circuit is proposed here. In the prototype built, the equivalent inertial mass of the pendulum is obtained from the measurement of the position of the moving assembly and the electrical quantities (electromotive force and current) on a coil as a function of time. The prototype has demonstrated the functionality of the method, identifying some operative limits for an implementation aimed at the measurement at the metrological level.

I. Introduction

Monitoring the kilogram and measuring related fundamental constants are now a problem of great relevance for the likely decision of redefining the mass unit or introducing even more radical changes in the SI system structure [1]. In fact, the last General Conference on Weights and Measures (GCPM) recommended that [2] “National Metrology Institutes and the BIPM pursue the relevant experiments, so that the International Committee can come to a view on whether it may be possible to redefine the kilogram, the ampere, the kelvin, and the mole using fixed values of the fundamental constants at the time of the 24th General Conference (2011).”