An Introduction to the New SI

  title={An Introduction to the New SI},
  author={S M Knotts and Peter J. Mohr and William D. Phillips},
  journal={The Physics Teacher},
Plans are under way to redefine the International System of Units (SI) around 2018. The new SI specifies the values of certain physical constants to define units. This article explains the new SI in order to provide a resource for high school teachers as well as for advanced students already familiar with the pre-2018 SI. 

A critical review of the CCU 2016 Draft of the Brochure for the New SI definition using (fundamental) constants

Though this draft is advanced with respect to the CCU 2013 Draft, it is shown how the description of the complex structure of the new definition may still be difficult to be clearly caught even by informed readers, while most users might be lost about their tasks needed to implement the new definitions.

The SI-Gap: How British Units Are Impeding Advances in STEM

The United States is one of only three countries in the world that remain uncommitted to the metric system. Perhaps to policymakers the decision to hang on to miles, pounds, and gallons is one of

Determining the value of the fine-structure constant from a current balance: Getting acquainted with some upcoming changes to the SI

The revised International System of Units (SI), expected to be approved late in 2018, has implications for physics pedagogy. The ampere definition, which dates from 1948, will be replaced by a

Development of Electrical Quantities Primary Standards

  • R. Ali
  • Physics
    Trans. Inst. Meas. Control
  • 2022
The developments of primary standards for electrical quantities that practically realize the electrical units such as ampere (A), volt (V), ohm (Ω), and farad (F) are introduced in this manuscript.

Physical analysis of an electric resistor heating

This work describes a simple experiment to measure the resistor temperature as a function of the applied power and proves that it is an efficient way to introduce some important physical concepts in

Unified presentation of four fundamental inequalities

We suggest an unified presentation to teach fundamental constants to graduate students, by introducing four lower limits to observed phenomena. The reduced Planck constant ℏ is the lowest classically



Towards a new SI: a review of progress made since 2011

In 2011, the General Conference on Weights and Measures (CGPM) confirmed its intention to adopt new definitions for four of the base units of the SI based on fixed numerical values of selected

About the International System of Units (SI) Part I. Introduction and Bibliography

Since much of SI is based on physics and mathematics, physics teachers have the background to teach SI. We present this review and summary in a series of SI notes in order to help teachers answer

Defining units in the quantum based SI

Possible changes to the International System of Units (SI) are being discussed, including a proposal to define the units by specifying the values of a set of fundamental constants. This note is an

A LEGO Watt balance: An apparatus to determine a mass based on the new SI

The design, construction, and performance of the LEGO watt balance and its ability to determine h, the Planck constant, are presented.

Resource Letter FC-1: The physics of fundamental constants

This Resource Letter provides a guide to the literature on the physics of fundamental constants and their values as determined within the International System of Units (SI). Journal articles, books,

CODATA recommended values of the fundamental constants

A review is given of the latest Committee on Data for Science and Technology (CODATA) adjustment of the values of the fundamental constants, referred to as the 1998 values, which replaces the values recommended for international use by CODATA in 1986.

A more fundamental International System of Units

The universally accepted method of expressing physical measurements for world commerce, industry, and science is about to get a facelift, thanks to our improved knowledge of fundamental constants.

A simple watt balance for the absolute determination of mass

A watt balance is an electromechanical device that allows a mass to be determined in terms of measurable electrical and mechanical quantities, themselves traceable to the fundamental constants of

Adapting the International System of Units to the twenty-first century

The objective of the proposed changes is to adopt definitions referenced to constants of nature, taken in the widest sense, so that the definitions may be based on what are believed to be true invariants.