Français
1. International System (SI)
It includes seven base units, designed to measure independent physical quantities and adopted internationally by the General Conference on Weights and Measures. They are derived units that are products of powers of the base units. As a reminder, these SI base and derived units are based on seven physical constants.
1.1 Constants
The seven constants defining the SI have been chosen so that any SI unit can be expressed in terms of one of the seven constants, or in terms of products or ratios of these constants. Thus, the SI is the system of units according to which :
the frequency of the hyperfine transition of the ground state of the unperturbed cesium 133 atom (∆ν Cs ) is equal...
The Ultimate Scientific and Technical Reference
This article is included in
Preparing for construction
This offer includes:
Knowledge Base
Updated and enriched with articles validated by our scientific committees
Services
A set of exclusive tools to complement the resources
Practical Path
Operational and didactic, to guarantee the acquisition of transversal skills
Doc & Quiz
Interactive articles with quizzes, for constructive reading
International System (SI)
Definitions and symbols
Regulations
Laws
Law of July 4, 1837, amended by the law of July 15, 1944, relating to the metric system and the verification of weights and measures.
Law of April 2, 1919 on units of measurement, amended by the law of January 14, 1948.
Decrees
Decree no. 61-501 of May 3, 1961 (OJ of May 20, 1961 corrected August 11, 1961) and amended by...
The Ultimate Scientific and Technical Reference
