Fundamental Physical Constants — Extensive Listing Relative Std
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2019 Redefinition of SI Base Units
2019 redefinition of SI base units A redefinition of SI base units is scheduled to come into force on 20 May 2019.[1][2] The kilogram, ampere, kelvin, and mole will then be defined by setting exact numerical values for the Planck constant (h), the elementary electric charge (e), the Boltzmann constant (k), and the Avogadro constant (NA), respectively. The metre and candela are already defined by physical constants, subject to correction to their present definitions. The new definitions aim to improve the SI without changing the size of any units, thus ensuring continuity with existing measurements.[3][4] In November 2018, the 26th General Conference on Weights and Measures (CGPM) unanimously approved these changes,[5][6] which the International Committee for Weights and Measures (CIPM) had proposed earlier that year.[7]:23 The previous major change of the metric system was in 1960 when the International System of Units (SI) was formally published. The SI is a coherent system structured around seven base units whose definitions are unconstrained by that of any other unit and another twenty-two named units derived from these base units. The metre was redefined in terms of the wavelength of a spectral line of a The SI system after the 2019 redefinition: krypton-86 radiation,[Note 1] making it derivable from universal natural Dependence of base unit definitions onphysical constants with fixed numerical values and on other phenomena, but the kilogram remained defined in terms of a physical prototype, base units. leaving it the only artefact upon which the SI unit definitions depend. The metric system was originally conceived as a system of measurement that was derivable from unchanging phenomena,[8] but practical limitations necessitated the use of artefacts (the prototype metre and prototype kilogram) when the metric system was first introduced in France in 1799. -
Arxiv:0801.0028V1 [Physics.Atom-Ph] 29 Dec 2007 § ‡ † (People’S China Metrology, Of) of Lic Institute Canada National Council, Zhang, Research Z
CODATA Recommended Values of the Fundamental Physical Constants: 2006∗ Peter J. Mohr†, Barry N. Taylor‡, and David B. Newell§, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8420, USA (Dated: March 29, 2012) This paper gives the 2006 self-consistent set of values of the basic constants and conversion factors of physics and chemistry recommended by the Committee on Data for Science and Technology (CODATA) for international use. Further, it describes in detail the adjustment of the values of the constants, including the selection of the final set of input data based on the results of least-squares analyses. The 2006 adjustment takes into account the data considered in the 2002 adjustment as well as the data that became available between 31 December 2002, the closing date of that adjustment, and 31 December 2006, the closing date of the new adjustment. The new data have led to a significant reduction in the uncertainties of many recommended values. The 2006 set replaces the previously recommended 2002 CODATA set and may also be found on the World Wide Web at physics.nist.gov/constants. Contents 3. Cyclotron resonance measurement of the electron relative atomic mass Ar(e) 8 Glossary 2 4. Atomic transition frequencies 8 1. Introduction 4 1. Hydrogen and deuterium transition frequencies, the 1. Background 4 Rydberg constant R∞, and the proton and deuteron charge radii R , R 8 2. Time variation of the constants 5 p d 1. Theory relevant to the Rydberg constant 9 3. Outline of paper 5 2. Experiments on hydrogen and deuterium 16 3. -
Conventioral Standards?* JESSE W
156 IRE TRANSACTIONS ON INSTRUMENTATION December Present Status of Precise Information on the Universal Physical Constants. Has the Time Arrived for Their Adoption to Replace Our Present Arbitrary Conventioral Standards?* JESSE W. M. DuMONDt INTRODUCTION this subject that the experimentally measured data r HREE years ago Dr. E. R. Cohen and I prepared often do not give the desired unknowns directly but and published our latest (1955) least-squares ad- instead give functions of the unknowns. justment of all the most reliable data then avail- Seven different functions of these above four un- able bearing on the universal constants of physics and knowns have been measured by experimental methods chemistry. Since then new data and information have which we feel are sufficiently precise and reliable to been accumulating so that a year or two from now the qualify them as input data in a least-squares adjust- time may perhaps be propitious for us to prepare a new ment. These seven experimentally determined numeri- adjustment taking the newly-gained knowledge into cal values are not only functions of the unknowns,ae, account. At present it is too early to attempt such a e, N, and A, but also of the above-mentioned experi re-evaluation since many of the investigations and re- mentally determined auxiliary constants, of which five determinations now under way are still far from com- different kinds are listed in Table I. Another of these pleted. I shall be obliged, therefore, to content myself auxiliary constants I find it expedient to recall to your in this talk with a description of the sources of informa- attention at the very beginning to avoid any possibility tion upon which our 1955 evaluation was based, men- of confusion. -
The Discovery of Thermodynamics
Philosophical Magazine ISSN: 1478-6435 (Print) 1478-6443 (Online) Journal homepage: https://www.tandfonline.com/loi/tphm20 The discovery of thermodynamics Peter Weinberger To cite this article: Peter Weinberger (2013) The discovery of thermodynamics, Philosophical Magazine, 93:20, 2576-2612, DOI: 10.1080/14786435.2013.784402 To link to this article: https://doi.org/10.1080/14786435.2013.784402 Published online: 09 Apr 2013. Submit your article to this journal Article views: 658 Citing articles: 2 View citing articles Full Terms & Conditions of access and use can be found at https://www.tandfonline.com/action/journalInformation?journalCode=tphm20 Philosophical Magazine, 2013 Vol. 93, No. 20, 2576–2612, http://dx.doi.org/10.1080/14786435.2013.784402 COMMENTARY The discovery of thermodynamics Peter Weinberger∗ Center for Computational Nanoscience, Seilerstätte 10/21, A1010 Vienna, Austria (Received 21 December 2012; final version received 6 March 2013) Based on the idea that a scientific journal is also an “agora” (Greek: market place) for the exchange of ideas and scientific concepts, the history of thermodynamics between 1800 and 1910 as documented in the Philosophical Magazine Archives is uncovered. Famous scientists such as Joule, Thomson (Lord Kelvin), Clau- sius, Maxwell or Boltzmann shared this forum. Not always in the most friendly manner. It is interesting to find out, how difficult it was to describe in a scientific (mathematical) language a phenomenon like “heat”, to see, how long it took to arrive at one of the fundamental principles in physics: entropy. Scientific progress started from the simple rule of Boyle and Mariotte dating from the late eighteenth century and arrived in the twentieth century with the concept of probabilities. -
Fundamental Constants
Appendix A Fundamental Constants Table A.1 Fundamental constants Quantity & symbol CGS MKS (SI) Speed of light in vacuum c 2.997925 1010 cm sec−1 108 ms−1 −7 −6 −1 Magnetic constant μ0 = 4π × 10 1.25664 10 Hm (permeability of free space) 2 −12 −1 Electric constant 0 = 1/μ0c 8.8541853 10 Fm (permittivity of free space) Electron charge e 1.60219 10−19 C 4.80324 10−10 esu Electron volt eV 1.60219 10−12 erg eV−1 10−19 JeV−1 −28 −31 Electron rest mass m0 9.10956 10 gm 10 kg Planck’s constant h 6.626196 10−27 erg sec 10−34 Js Planck’s constant = h/2π 1.05459 10−27 erg sec 10−34 Js 2 2 −8 −10 Bohr radius a0 = 4π0 /m0e 0.529177 10 cm 10 m = 2 2 Rydberg constant Ry /2m0a0 13.6058 eV eV Fine structure constant 7.297351 10−3 10−3 2 α = e /20hc 23 −1 23 −1 Avogadro’s constant L,NA 6.022169 10 mol 10 mol 25 −3 Loschmidt’s constant NL 2.68719 10 m −16 −1 −23 −1 Boltzmann’s constant kB = R/L 1.380622 10 erg K 10 JK Faraday constant F = Le 9.64867 104 Cmol−1 7 −1 −1 −1 −1 Universal gas constant R = LkB 8.31435 10 erg K mol JK mol Mechanical equivalent of heat 4.184 107 erg cal−1 J cal−1 −21 −1 −24 −1 Bohr magneton μB = e/2m0c 9.2741 10 erg G 10 JT −24 −27 Proton rest mass mp 1.67251 10 gm 10 kg −24 −1 −27 −1 Nuclear magneton μN = e/2mpc 5.0508 10 erg G 10 JT −24 −27 Neutron rest mass mn 1.67492 10 gm 10 kg Stefan-Boltzmann constant 5.6697 10−8 Wm−2 K−4 = 5 4 3 2 σ 2π kB /15h c Y. -
Molar Mass 1 Molar Mass
Molar mass 1 Molar mass In chemistry, the molar mass is a physical property. It is defined as the mass of a given substance (chemical element or chemical compound) divided by its amount of substance. The base SI unit for molar mass is kg/mol. However, for historical reasons, molar masses are almost always expressed in g/mol. As an example, the molar mass of water is approximately: M(H O) ≈ 18 g⋅mol−1 2 Molar masses of elements The molar mass of atoms of an element is given by the atomic mass of the element multiplied by the molar mass constant, M −3 u = 1×10 kg/mol = 1 g/mol: M(H) = 1.007 97(7) × 1 g/mol = 1.007 97(7) g/mol M(S) = 32.065(5) × 1 g/mol = 32.065(5) g/mol M(Cl) = 35.453(2) × 1 g/mol = 35.453(2) g/mol M(Fe) = 55.845(2) × 1 g/mol = 55.845(2) g/mol. Multiplying by the molar mass constant ensures that the calculation is dimensionally correct: atomic weights are dimensionless quantities (i.e., pure numbers) whereas molar masses have units (in this case, grams/mole). Some elements are usually encountered as molecules, e.g. hydrogen (H 2), sulfur (S 8), chlorine (Cl 2). The molar mass of molecules of these elements is the molar mass of the atoms multiplied by the number of atoms in each molecule: M(H 2) = 2 × 1.007 97(7) × 1 g/mol = 2.015 88(14) g/mol M(S 8) = 8 × 32.065(5) × 1 g/mol = 256.52(4) g/mol M(Cl 2) = 2 × 35.453(2) × 1 g/mol = 70.906(4) g/mol. -
Fundamental Physical Constants — Complete Listing Relative Std
From: http://physics.nist.gov/constants Fundamental Physical Constants — Complete Listing Relative std. Quantity Symbol Value Unit uncert. ur UNIVERSAL 1 speed of light in vacuum c; c0 299 792 458 m s− (exact) 7 2 magnetic constant µ0 4π 10− NA− × 7 2 = 12:566 370 614::: 10− NA− (exact) 2 × 12 1 electric constant 1/µ0c "0 8:854 187 817::: 10− F m− (exact) characteristic impedance × of vacuum µ / = µ c Z 376:730 313 461::: Ω (exact) p 0 0 0 0 Newtonian constant 11 3 1 2 3 of gravitation G 6:673(10) 10− m kg− s− 1:5 10− × 39 2 2 × 3 G=¯hc 6:707(10) 10− (GeV=c )− 1:5 10− × 34 × 8 Planck constant h 6:626 068 76(52) 10− J s 7:8 10− × 15 × 8 in eV s 4:135 667 27(16) 10− eV s 3:9 10− × 34 × 8 h=2π ¯h 1:054 571 596(82) 10− J s 7:8 10− × 16 × 8 in eV s 6:582 118 89(26) 10− eV s 3:9 10− × × 1=2 8 4 Planck mass (¯hc=G) mP 2:1767(16) 10− kg 7:5 10− 3 1=2 × 35 × 4 Planck length ¯h=mPc = (¯hG=c ) lP 1:6160(12) 10− m 7:5 10− 5 1=2 × 44 × 4 Planck time lP=c = (¯hG=c ) tP 5:3906(40) 10− s 7:5 10− × × ELECTROMAGNETIC 19 8 elementary charge e 1:602 176 462(63) 10− C 3:9 10− × 14 1 × 8 e=h 2:417 989 491(95) 10 AJ− 3:9 10− × × 15 8 magnetic flux quantum h=2e Φ0 2:067 833 636(81) 10− Wb 3:9 10− 2 × 5 × 9 conductance quantum 2e =h G0 7:748 091 696(28) 10− S 3:7 10− 1 × × 9 inverse of conductance quantum G0− 12 906:403 786(47) Ω 3:7 10− a 9 1 × 8 Josephson constant 2e=h KJ 483 597:898(19) 10 Hz V− 3:9 10− von Klitzing constantb × × 2 9 h=e = µ0c=2α RK 25 812:807 572(95) Ω 3:7 10− × 26 1 8 Bohr magneton e¯h=2me µB 927:400 899(37) 10− JT− 4:0 10− 1 × 5 1 × 9 in -
List of Symbols
Appendix A List of Symbols For convenience, many symbols frequently used in the text are listed below alphabetically. Some of the symbols may play a dual role, in which case the meaning should be obvious from the context. A number in parentheses refers to an Eq. number (or the text or footnote near that Eq. number) in which the symbol is defined or appears for the first time; in a few cases a page number, Table number, Sect. number, footnote (fn.) number, or Fig. number is given instead. Quantum number is abbreviated as q. n. Quantum numbers (atomic): Symbol Description Eq. No. j D l ˙ s Inner q. n. of an electron (3.13) J D L C S Inner (total angular momentum) q. n. of a state (5.51b) l P Azimuthal (orbital) q. n. of an electron (3.1) and (3.2) L D l Azimuthal (orbital) q. n. of a state (5.51c) ml Magnetic orbital q. n. of an electron (3.1) ms Magnetic spin q. n. of an electron (3.1) M Total magnetic q. n. (5.51d) n Principal q. n. of an electron (3.1) s P Spin q. n. of an electron (3.13) S D s Spin q. n. of a state (5.51e) Relativistic azimuthal q. n. of an electron (3.15a) and (3.15b) Relativistic magnetic q. n. of an electron (3.18a) and (3.18b) W.F. Huebner and W.D. Barfield, Opacity, Astrophysics and Space Science Library 402, 457 DOI 10.1007/978-1-4614-8797-5, © Springer Science+Business Media New York 2014 458 Appendix A: List of Symbols Quantum numbers (molecular)1: Symbol Description Eq. -
Status of the Redefinition of the Mole
Status of the redefinition of the mole Dr. Bernd Güttler Physikalisch-Technische Bundesanstalt (PTB) Germany CCQM WG on the mole Symposium at 250th ACS National Meeting, Boston, MA, August 19, 2015 page 1 of X Definition of the mole "Let us generally refer to the weight in Wilhelm Ostwald grams of a substance that is numerically identical to the molecular weight of that substance, as one mole...” relation to the international system of units (later called SI) is established unit of mass, no relation to particle number at this stage Symposium at 250th ACS National Meeting, Boston, MA, August 19, 2015 page 2 of X Definition of the mole The mole, mol, is the unit of amount of substance of a specified elementary entity, which may be an atom, molecule, ion, electron, any other particle or a specified group of such particles; "Let us generally refer to the weight in its magnitude is set by fixing the grams of a substance that is numerically numerical value of the Avogadro identical to the molecular weight of that constant to be equal to exactly 6.022 substance, as one mole...” 141X·1023 when it is expressed in the unit mol-1. Ostwald 1893 ? proposed definition Symposium at 250th ACS National Meeting, Boston, MA, August 19, 2015 page 3 of X Definition of the mole "Let us generally refer to the weight in grams of a substance that is numerically M(X) = Ar(X) x Mu identical to the molecular weight of that substance, as one mole...” nx = Mx/M(X) M(X) molar mass of X Ar(X) Σ rel. -
Modernizing the SI – Implications of Recent Progress with the Fundamental Constants Nick Fletcher, Richard S
Modernizing the SI – implications of recent progress with the fundamental constants Nick Fletcher, Richard S. Davis, Michael Stock and Martin J.T. Milton, Bureau International des Poids et Mesures (BIPM), Pavillon de Breteuil, 92312 Sèvres CEDEX, France. e-mail : [email protected] Abstract Recent proposals to re-define some of the base units of the SI make use of definitions that refer to fixed numerical values of certain constants. We review these proposals in the context of the latest results of the least-squares adjustment of the fundamental constants and against the background of the difficulty experienced with communicating the changes. We show that the benefit of a definition of the kilogram made with respect to the atomic mass constant (mu) may now be significantly stronger than when the choice was first considered 10 years ago. Introduction The proposal to re-define four of the base units of the SI with respect to fixed numerical values of four constants has been the subject of much discussion and many publications. Although the possibility had been foreseen in publications during the 1990’s [1] they were not articulated as a complete set of proposals until 2006 [2]. Subsequently, the General Conference on Weights and Measures, the forum for decision making between the Member States of the BIPM on all matters of measurement science and measurement units, addressed the matter at its 23rd meeting in 2007. It recognised the importance of considering such a re- definition, and invited the NMIs to “come to a view on whether it is possible”. More recently at its 24th meeting in 2011, it noted that progress had been made towards such a re-definition and invited a final proposal when the experimental data were sufficiently robust to support one. -
Definition of the Mole
IUPAC Definition of the mol e For Peer Review Only Journal: Pure and Applied Chemistry Manuscript ID PAC-REC-17-01-06 Manuscript Type: Recommendation Date Submitted by the Author: 11-Jan-2017 Complete List of Authors: Marquardt, Roberto; Université Louis Pasteur, Laboratoire de Chimie Quantique Theorique Meija, Juris; National Research Council Canada, Measurement Science and Standards Mester, Zoltan; National Research Council of Canada, Institute for National Measurement Standards Towns, Marcy; Purdue University System, Department of Chemistry Weir, Ron; Royal Military College of Canada, Dep. of Chemistry & Chemical Engineering Davis, Richard Stohner, Jürgen; ZHAW Zürich Univ. for Applied Sciences, ICBC Institute for Chemistry and Biological Chemistry; ETH-Zürich, Physical Chemistry Keywords: the mole, definition, Avogadro constant, Avogadro number Author-Supplied Keywords: P.O. 13757, Research Triangle Park, NC (919) 485-8700 Page 1 of 5 IUPAC Pure Appl. Chem. 201X; aop 1 2 3 Sponsoring bodies: IUPAC Physical and Biophysical Chemistry Division, IUPAC Inorganic Chemistry Division, IUPAC Analyt- 4 ical Chemistry Division, IUPAC Committee on Chemistry Education, and IUPAC Interdivisional Committee on Terminology, 5 Nomenclature and Symbols: see more details on page XXX. 6 IUPAC Provisional Recommendation 7 8 9 Roberto Marquardt, Juris Meija, Zoltán Mester, Marcy Towns, Ron Weir, Richard Davis, 10 and Jürgen Stohner* 11 12 Definition of the mole (IUPAC Provisional 13 14 For Peer Review Only 15 Recommendation 201X) 16 17 18 DOI: 10.1515/pac-201X-XXXX, Received ...; accepted ... 19 Abstract: In 2011 the General Conference on Weights and Measures (CGPM) noted the intention of the 20 21 International Committee of Weights and Measures (CIPM) to revise the entire International System of 22 Units (SI) by linking all seven base units to seven fundamental physical constants. -
Chapter 1 Elementary Kinetic Theory of Gases
Chapter 1 Elementary kinetic theory of gases 1.1. Introduction. Molecular description of gases 1.2. Molecular quantities and macroscopic gas parameters 1.3. Gas laws 1.4. Collision frequency. Free molecular, transitional, and continuum flow regimes 1.5. Transfer of molecular quantities 1.6. Transfer equation 1.7. Diffusion, viscous drag, and heat conduction 1.8. Appendix: Probability and Bernoulli trial ME 591, Non‐equilibrium gas dynamics, Alexey Volkov 1 1.1. Introduction. Molecular description of gases Subject of kinetic theory. What are we going to study? Historical perspective Hypothesis of molecular structure of gases Sizes of atoms and molecules Masses of atoms and molecules Properties of major components of atmospheric air and other gases Length and time scale of inter‐molecular collisions Characteristic distance between molecules in gases Density parameter. Dilute and dense gases Purpose of the kinetic theory Chaotic motion of molecules. Major approach of the kinetic theory Specific goals of the kinetic theory Applications of the kinetic theory and RGD ME 591, Non‐equilibrium gas dynamics, Alexey Volkov 2 1.1. Introduction. Molecular description of gases Subject of kinetic theory. What are we going to study? Kinetic theory of gases is a part of statistical physics where flows of gases are considered on the molecular level, i.e. on the level of individual molecules, and described in terms of changes of probabilities of various states of gas molecules in space and time based on known laws of interaction between individual molecules. Word “Kinetic” came from a Greek verb meaning "to move“ or “to induce a motion.” Rarefiedgasdynamics(RGD)is often used as a synonymous of the kinetic theory of gases.