International System of Units

1 Page 1 NIST Special Publication 330 The International System of Units (SI) 2019 EDITION SP 330 David B. Newell and Eite Tiesinga, Editors This publication is available free of charge https://doi.org/10.6028/NIST.SP.330-2019 Open at page → 2 Page 2 This publication is available free of charge from: https://doi.org/10.6028/NIST.SP.330-2019 INSIDE FRONT COVER - BLANK Open at page → 3 Page 3 NIST Special Publication 330 2019 EDITION The International System of Units (SI) United States version of the English text of the ninth edit ion (2019) of the International Bureau of Weights and Measures publication Le S... Open at page → 4 Page 4 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP .330 - 2019 Certain commercial entities, equipment, or materials may be identified in this document in order to describe an experimental... Open at page → 5 Page 5 iii This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 Foreword The International System of Units, universally abbreviated SI (from the French Le Système International d’Unité... Open at page → 6 Page 6 iv This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 •A few very minor editorial changes are made in order to “Americanize” some phrases. Because of the importance of the SI... Open at page → 7 Page 7 v This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 The BIPM and the Meter Convention The International Bureau of Weights and Measures (BIPM) was set up by the Meter Conventi... Open at page → 8 Page 8 vi This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 The activities of the BIPM, which in the beginning were limited to measurements of length and mass, and to metrological s... Open at page → 9 Page 9 vii This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 (CCEMRI) set up in 1958 (in 1969 this committee established four sections: Section I (x and γ rays, electrons), Section... Open at page → 10 Page 10 viii This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 This page intentionally left blank. Open at page → 11 Page 11 ix This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 Table of Contents Preface to the 9 th edition .............................................................................. Open at page → 12 Page 12 x This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 Appendix 4. Historical notes on the development of the International System of Units and its base units ..................... Open at page → 13 Page 13 xi This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 Preface to the 9 th edition The International System of Units, the SI, has been used around the world as the preferred sy... Open at page → 14 Page 14 xii This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 We draw attention to the fact that since its establishment in 1960, the International System of Units has always been re... Open at page → 15 Page 15 xiii This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 Note on the text: The 22nd meeting of the CGPM decided, in 2003, following a decision of the CIPM in 1997, that “the sy... Open at page → 16 Page 16 xiv This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 This page intentionally left blank. Open at page → 17 Page 17 1 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 1. Introduction 1.1 The SI and the defining constants This brochure presents information on the definition and use of the... Open at page → 18 Page 18 2 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 experimental prescriptions as in the case of the ampere and the candela; or constants of nature such as the speed of light... Open at page → 19 Page 19 3 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 2. The International System of Units 2.1 Defining the unit of a quantity The value of a quantity is generally expressed as... Open at page → 20 Page 20 4 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 • the Avogadro constant N A is 6.022 140 76 × 10 23 mol −1 , • the luminous efficacy of monochromatic radiation of frequen... Open at page → 21 Page 21 5 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 uncertainties. The technical conventions and specifications also take historical developments into account. Both the Planc... Open at page → 22 Page 22 6 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 2.3.1 Base units The base units of the SI are listed in Table 2. Table 2. SI base units Base quantity Base unit Name Typic... Open at page → 23 Page 23 7 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 The second, so defined, is the unit of proper time in the sense of the general theory of relativity. To allow the provisio... Open at page → 24 Page 24 8 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 The effect of this definition is to define the unit kg m 2 s −1 (the unit of both the physical quantities action and angul... Open at page → 25 Page 25 9 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 permeability μ 0 (also known as the magnetic constant) to be exactly 4π × 10 −7 H m −1 = 4π × 10 −7 N A −2 , where H and N... Open at page → 26 Page 26 10 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 reference temperature T 0 = 273.15 K, close to the ice point. This difference is called the Celsius temperature, symbol t... Open at page → 27 Page 27 11 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 The previous definition of the mole fixed the value of the molar mass of carbon-12, M( 12 C), to be exactly 0.012 kg/mol.... Open at page → 28 Page 28 12 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 This definition implies the exact relation K cd = 683 cd sr kg −1 m −2 s 3 for monochromatic radiation of frequency ν = 5... Open at page → 29 Page 29 13 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 2.3.3 Dimensions of quantities Physical quantities can be organized in a system of dimensions, where the system used is d... Open at page → 30 Page 30 14 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 There are also some quantities that cannot be described in terms of the seven base quantities of the SI, but have the nat... Open at page → 31 Page 31 15 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 Table 4. The 22 SI units with special names and symbols Derived quantity Special name of unit Unit expressed in terms of... Open at page → 32 Page 32 16 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 (a) The order of symbols for base units in this Table is different from that in the 8th edition following a decision by t... Open at page → 33 Page 33 17 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 Table 5. Examples of coherent derived units in the SI expressed in terms of base units Derived quantity Typical symbol of... Open at page → 34 Page 34 18 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 Table 6. Examples of SI coherent derived units whose names and symbols include SI coherent derived units with special nam... Open at page → 35 Page 35 19 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 It is important to emphasize that each physical quantity has only one coherent SI unit, even though this unit can be expr... Open at page → 36 Page 36 20 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 1 o C, but for an absolute temperature the difference of 273.15 K must be taken into account. The unit degree Celsius is... Open at page → 37 Page 37 21 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 standards of about 1 part in 10 16 per meter of altitude difference at the surface of the earth. Effects of this magnitud... Open at page → 38 Page 38 22 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 This page intentionally left blank. Open at page → 39 Page 39 23 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 3. Decimal multiples and sub- multiples of SI units Decimal multiples and submultiples ranging from 10 24 to 10 −24 are p... Open at page → 40 Page 40 24 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 Compound prefix symbols, i.e. prefix symbols formed by the juxtaposition of two or more prefix symbols, are not permitted... Open at page → 41 Page 41 25 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 4. Non-SI units that are accepted for use with the SI The SI provides the internationally agreed reference in terms of wh... Open at page → 42 Page 42 26 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 (a) As decided at the XXVIII General Assembly of the International Astronomical Union (Resolution B2, 2012). (b) For some... Open at page → 43 Page 43 27 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 Table 8 also includes the units of logarithmic ratio quantities, the neper, bel and decibel. They are used to convey info... Open at page → 44 Page 44 28 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 This page intentionally left blank. Open at page → 45 Page 45 29 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 5. Writing unit symbols and names, and expressing the values of quantities 5.1 The use of unit symbols and names General... Open at page → 46 Page 46 30 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 is mandatory. In this way ambiguities and misunderstandings in the values of quantities are avoided. 5.3 Unit names Unit... Open at page → 47 Page 47 31 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 Symbols for units are treated as mathematical entities. In expressing the value of a quantity as the product of a numeric... Open at page → 48 Page 48 32 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 5.4.3 Formatting the value of a quantity The numerical value always precedes the unit and a space is always used to separ... Open at page → 49 Page 49 33 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 5.4.5 Expressing the measurement uncertainty in the value of a quantity The uncertainty associated with an estimated valu... Open at page → 50 Page 50 34 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 Quantities that are ratios of quantities of the same kind (for example length ratios and amount fractions) have the optio... Open at page → 51 Page 51 35 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 The solid angle, expressed in steradian, corresponds to the ratio between an area A of the surface of a sphere of radius... Open at page → 52 Page 52 36 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 This page intentionally left blank. Open at page → 53 Page 53 37 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 Appendix 1. Decisions of the CGPM and the CIPM This appendix lists those decisions of the CGPM and the CIPM that bear dir... Open at page → 54 Page 54 38 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 Table of Contents of Appendix 1 Decisions relating to the establishment of the SI Page 9th CGPM, 1948: decision to establ... Open at page → 55 Page 55 39 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 CIPM, 2009: updates to the list of standard frequencies 89 24th CGPM, 2011: possible future revision of the International... Open at page → 56 Page 56 40 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 CIPM, 2006: secondary representations of the second 84 23rd CGPM, 2007: on the revision of the mise en pratique of the de... Open at page → 57 Page 57 41 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 CIPM, 1948: adopts the name degree Celsius for the Celsius temperature scale 49 10th CGPM, 1954: degree Kelvin adopted as... Open at page → 58 Page 58 42 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 24th CGPM, 2011: possible future revision of the International System of Units, the SI 89 26th CGPM, 2018: revision of th... Open at page → 59 Page 59 43 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 11th CGPM, 1960: requests the CIPM to report on the difference between the liter and the cubic decimeter 54 CIPM, 1961: r... Open at page → 60 Page 60 44 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 This page intentionally left blank. Open at page → 61 Page 61 45 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 1st CGPM, 1889  Sanction of the international prototypes of the meter and the kilogram (CR, 34 - 38) * The Conférence Gé... Open at page → 62 Page 62 46 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 3rd CGPM, 1901  Declaration concerning the definition of the liter (CR, 38-39) * … The Conference declares 1. The unit o... Open at page → 63 Page 63 47 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 7th CGPM, 1927  Definition of the meter by the international Prototype (CR, 49)* The unit of length is the meter, define... Open at page → 64 Page 64 48 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 Joule (unit of energy or work). — The joule is the work done when the point of application of 1 MKS unit of force [newton... Open at page → 65 Page 65 49 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 9th CGPM, 1948  Triple point of water; thermodynamic scale with a single fixed point; unit of quantity of heat (joule) (... Open at page → 66 Page 66 50 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019  Proposal for establishing a practical system of units of measurement (CR, 64) Resolution 6 The Conférence Générale des... Open at page → 67 Page 67 51 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 Unit Symbol Unit Symbol • meter m ampere A • square meter m 2 volt V • cubic meter m 3 watt W • micron µ ohm Ω • liter 9... Open at page → 68 Page 68 52 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 10th CGPM, 1954  Definition of the thermodynamic temperature scale (CR, 79) * Resolution 3 The 10th Conférence Générale... Open at page → 69 Page 69 53 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 CIPM, 1956  Definition of the unit of time (second) (PV, 25, 77)* Resolution 1 In virtue of the powers invested in it by... Open at page → 70 Page 70 54 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 2. that the units listed in the table below be used, without excluding others which might be added later: [This is follow... Open at page → 71 Page 71 55 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 “The second is the fraction 1/31 556 925.9747 of the tropical year for 1900 January 0 at 12 hours ephemeris time.”  Syst... Open at page → 72 Page 72 56 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 4. the units listed below are used in the system, without excluding others which might be added later. Supplementary unit... Open at page → 73 Page 73 57 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019  Cubic decimeter and liter (CR, 88) Resolution 13 The 11th Conférence Générale des Poids et Mesures (CGPM), considering... Open at page → 74 Page 74 58 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 12th CGPM, 1964  Atomic standard of frequency (CR, 93) Resolution 5 The 12th Conférence Générale des Poids et Mesures (C... Open at page → 75 Page 75 59 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 considering that the curie has been used for a long time in many countries as unit of activity for radionuclides, recogni... Open at page → 76 Page 76 60 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 considering • that the definition of the second adopted by the Comité International des Poids et Mesures (CIPM) in 1956 (... Open at page → 77 Page 77 61 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 decides 1. the unit of thermodynamic temperature is denoted by the name “kelvin” and its symbol is “K”;** 2. the same nam... Open at page → 78 Page 78 62 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 “The candela is the luminous intensity , in the perpendicular direction, of a surface of 1/600 000 square meter of a blac... Open at page → 79 Page 79 63 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 considering that Resolution 12 of the 11th Conférence Générale des Poids et Mesures (CGPM) (1960), concerning the Système... Open at page → 80 Page 80 64 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019  International Atomic Time, function of CIPM (CR, 77-78 and Metrologia, 1972, 8, 35) Resolution 1 The 14th Conférence Gé... Open at page → 81 Page 81 65 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019  SI unit of amount of substance (mole) (CR, 78 and Metrologia, 1972, 8, 36)* Resolution 3 The 14th Conférence Générale d... Open at page → 82 Page 82 66 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 that this wide diffusion makes available to the users not only frequency standards but also International Atomic Time and... Open at page → 83 Page 83 67 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 Multiplying factor Prefix Symbol 10 15 peta P 10 18 exa E 16th CGPM, 1979  SI unit of luminous intensity (candela) (CR,... Open at page → 84 Page 84 68 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019  Special name for the SI unit of dose equivalent (sievert) (CR, 100 and Metrologia, 1980, 16, 56) * Resolution 5 The 16t... Open at page → 85 Page 85 69 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 CIPM, 1980  SI supplementary units (radian and steradian) (PV, 48, 24 and Metrologia, 1981, 17, 72) * Recommendation 1 T... Open at page → 86 Page 86 70 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 17th CGPM, 1983  Definition of the meter (CR, 97 and Metrologia, 1984, 20, 25) Resolution 1 The 17th Conférence Générale... Open at page → 87 Page 87 71 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 decides 1. The meter is the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a... Open at page → 88 Page 88 72 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 kilogram for the unit of absorbed dose D and the name sievert instead of joules per kilogram for the unit of dose equival... Open at page → 89 Page 89 73 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 CIPM, 1988  Representation of the volt by means of the Josephson effect (PV, 56, 44 and Metrologia, 1989, 26, 69) Recomm... Open at page → 90 Page 90 74 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019  Representation of the ohm by means of the quantum Hall effect (PV, 56, 45 and Metrologia, 1989, 26, 70) Recommendation... Open at page → 91 Page 91 75 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 CIPM, 1989  The International Temperature Scale of 1990 (PV, 57, 115 and Metrologia, 1990, 27, 13) Recommendation 5 The... Open at page → 92 Page 92 76 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 Multiplying factor Prefix Symbol 10 21 zetta Z 10 −21 zepto z 10 24 yotta Y 10 −24 yocto y 20th CGPM, 1995  Elimination... Open at page → 93 Page 93 77 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 • the intrinsic uncertainty in the long-term stability of the artifact defining the unit of mass, one of the base units o... Open at page → 94 Page 94 78 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 “We suggest that “SI units” and “units of the SI” should be regarded as names that include both the base units and the co... Open at page → 95 Page 95 79 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 small that the effects of the non-uniformity of the gravitational field can be ignored (note that, at the surface of the... Open at page → 96 Page 96 80 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 welcomes validations now being made of comb techniques by comparison with other frequency chain techniques; urges nationa... Open at page → 97 Page 97 81 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 The Committee further decides to maintain the final sentence in the explanation as follows: In order to avoid any risk of... Open at page → 98 Page 98 82 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 • the value of a quantity is normally expressed as a number times a unit, • often the number in the expression of the val... Open at page → 99 Page 99 83 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 CIPM, 2005  Clarification of the definition of the kelvin, unit of thermodynamic temperature (PV, 73, 235 and Metrologia... Open at page → 100 Page 100 84 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 considering that: • improved frequency values for radiations of some high-stability cold ion and cold atom standards alre... Open at page → 101 Page 101 85 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 • the CCTF in its Recommendation CCTF 1 (2004) already recommended the unperturbed ground-state hyperfine quantum transit... Open at page → 102 Page 102 86 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 23rd CGPM, 2007  On the revision of the mise en pratique of the definition of the meter and the development of new optic... Open at page → 103 Page 103 87 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 • that the temperature of the triple point depends on the relative amount of isotopes of hydrogen and oxygen present in t... Open at page → 104 Page 104 88 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 • Resolution 7 of the 21st General Conference (1999) which recommended that "national laboratories continue their efforts... Open at page → 105 Page 105 89 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 formal proposals for changes in the definitions of the kilogram, ampere, the kelvin and mole can be put to the 24th Gener... Open at page → 106 Page 106 90 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 Resolution 1 The General Conference on Weights and Measures (CGPM), at its 24th meeting, considering • the international... Open at page → 107 Page 107 91 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 • that it is possible to redefine the kelvin so that it is linked to an exact numerical value of the Boltzmann constant k... Open at page → 108 Page 108 92 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 • the luminous efficacy K cd of monochromatic radiation of frequency 540 ×10 12 Hz is exactly 683 lumen per watt, where (... Open at page → 109 Page 109 93 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 • the existing definition of the second is linked to an exact value of a well -defined property of the cesium atom, which... Open at page → 110 Page 110 94 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 • the definition of the mole in force since 1971 (14th meeting of the CGPM, 1971, Resolution 3) based upon a definition w... Open at page → 111 Page 111 95 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 fulfilled, in particular the preparation of mises en pratique for the new definitions of the kilogram, ampere, kelvin and... Open at page → 112 Page 112 96 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 CIPM, 2013  Updates to the list of standard frequencies (PV , 81, 144) Recommendation 1 The International Committee for... Open at page → 113 Page 113 97 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 • that the following transition frequency be added to the list and as a secondary representation of the second: − the unp... Open at page → 114 Page 114 98 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 recalling • Resolution 1 adopted by the CGPM at its 24th meeting (2011), which takes note of the intention of the Interna... Open at page → 115 Page 115 99 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 encourages • continued effort in the NMIs, the BIPM, and academic institutions to obtain data relevant to the determinati... Open at page → 116 Page 116 100 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 uncertainty of 6 × 10 −16 (this radiation is already endorsed by the CIPM as a secondary representation of the second);... Open at page → 117 Page 117 101 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 with an estimated relative standard uncertainty of 5 × 10 −10 apply to the radiation of a tunable External Cavity Diode... Open at page → 118 Page 118 102 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 decides that, effective from 20 May 2019, the International System of Units, the SI, is the system of units in which • t... Open at page → 119 Page 119 103 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 • the definition of the mole in force since 1971 (14th meeting of the CGPM, Resolution 3) is abrogated, • the definition... Open at page → 120 Page 120 104 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 • The meter, symbol m, is the SI unit of length. It is defined by taking the fixed numerical value of the speed of light... Open at page → 121 Page 121 105 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 Appendix 2. Practical realization of the definitions of some important units Appendix 2 is published in electronic form... Open at page → 122 Page 122 106 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 Appendix 3. Units for photochemical and photobiological quantities Appendix 3 is published in electronic form only, and... Open at page → 123 Page 123 107 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 Appendix 4. Historical notes on the development of the International System of Units and its base units Part 1. The hist... Open at page → 124 Page 124 108 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 atoms or ions are now demonstrably more reproducible, by some orders of magnitude, than the defined frequency of cesium.... Open at page → 125 Page 125 109 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 ????????????= 8???????????? ???????????? 0 3 2???????????? ∞ℎ ???????????????????????? 2 ???????????? ??????????????????... Open at page → 126 Page 126 110 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 • The creation of the decimal metric system at the time of the French Revolution and the subsequent deposition of two pl... Open at page → 127 Page 127 111 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 International Union of Pure and Applied Physics (IUPAP) and other international organizations. This led the CCE to propo... Open at page → 128 Page 128 112 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 Part 3. Historical perspective on the base units Unit of time, second Before 1960, the unit of time the second, was defi... Open at page → 129 Page 129 113 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 some also to the BIPM. The 3rd CGPM (1901, CR, 70), in a declaration intended to end the ambiguity in common usage conce... Open at page → 130 Page 130 114 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 Unit of thermodynamic temperature, kelvin The definition of the unit of thermodynamic temperature was given by the 10th... Open at page → 131 Page 131 115 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 nS(X) = m S/M(X), and M(X) = A r(X) g/mol Thus, this definition of the mole was dependent on the artifact definition of... Open at page → 132 Page 132 116 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 This page intentionally left blank. Open at page → 133 Page 133 117 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 List of acronyms used in the present volume 1. Acronyms for laboratories, committees and conferences* BAAS British Assoc... Open at page → 134 Page 134 118 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 2. Acronyms for scientific terms CGS Three-dimensional coherent system of units based on the three mechanical units cent... Open at page → 135 Page 135 119 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 Index A absolute units, 113 absorbed dose, 15, 18, 19, 20, 42, 66, 68, 71, 80, 81 acceleration due to gravity, standard... Open at page → 136 Page 136 120 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 electron mass, 109 electronvolt (eV), 25, 26 elementary charge, 3, 4, 5, 8, 90, 91, 92, 98, 102, 104, 111, 113 erg., 51... Open at page → 137 Page 137 121 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 M magnetic constant, permeability of vacuum, 9, 94, 113 mandatory symbols for units, 30 mass, 6, 7, 8, 13, 25, 39, 45, 4... Open at page → 138 Page 138 122 This publication is available free of charge from: https://doi.org /10.6028/NIST.SP. 330 - 2019 95, 96, 97, 99, 100, 102, 103, 104, 107, 108, 109, 110, 111, 112 SI prefixes, 16, 23, 25, 26, 34, 42, 59, 63, 66, 75 SI,... Open at page →