Fundamental Physical Constants --- Complete Listing From: http://physics.nist.gov/constants Quantity Value Uncertainty Unit ------------------------------------------------------------------------------------------------------------------------ {220} lattice spacing of silicon 192.015 5762 e-12 0.000 0050 e-12 m alpha particle-electron mass ratio 7294.299 5365 0.000 0031 alpha particle mass 6.644 656 20 e-27 0.000 000 33 e-27 kg alpha particle mass energy equivalent 5.971 919 17 e-10 0.000 000 30 e-10 J alpha particle mass energy equivalent in MeV 3727.379 109 0.000 093 MeV alpha particle mass in u 4.001 506 179 127 0.000 000 000 062 u alpha particle molar mass 4.001 506 179 127 e-3 0.000 000 000 062 e-3 kg mol^-1 alpha particle-proton mass ratio 3.972 599 689 51 0.000 000 000 41 Angstrom star 1.000 014 98 e-10 0.000 000 90 e-10 m atomic mass constant 1.660 538 782 e-27 0.000 000 083 e-27 kg atomic mass constant energy equivalent 1.492 417 830 e-10 0.000 000 074 e-10 J atomic mass constant energy equivalent in MeV 931.494 028 0.000 023 MeV atomic mass unit-electron volt relationship 931.494 028 e6 0.000 023 e6 eV atomic mass unit-hartree relationship 3.423 177 7149 e7 0.000 000 0049 e7 E_h atomic mass unit-hertz relationship 2.252 342 7369 e23 0.000 000 0032 e23 Hz atomic mass unit-inverse meter relationship 7.513 006 671 e14 0.000 000 011 e14 m^-1 atomic mass unit-joule relationship 1.492 417 830 e-10 0.000 000 074 e-10 J atomic mass unit-kelvin relationship 1.080 9527 e13 0.000 0019 e13 K atomic mass unit-kilogram relationship 1.660 538 782 e-27 0.000 000 083 e-27 kg atomic unit of 1st hyperpolarizablity 3.206 361 533 e-53 0.000 000 081 e-53 C^3 m^3 J^-2 atomic unit of 2nd hyperpolarizablity 6.235 380 95 e-65 0.000 000 31 e-65 C^4 m^4 J^-3 atomic unit of action 1.054 571 628 e-34 0.000 000 053 e-34 J s atomic unit of charge 1.602 176 487 e-19 0.000 000 040 e-19 C atomic unit of charge density 1.081 202 300 e12 0.000 000 027 e12 C m^-3 atomic unit of current 6.623 617 63 e-3 0.000 000 17 e-3 A atomic unit of electric dipole mom. 8.478 352 81 e-30 0.000 000 21 e-30 C m atomic unit of electric field 5.142 206 32 e11 0.000 000 13 e11 V m^-1 atomic unit of electric field gradient 9.717 361 66 e21 0.000 000 24 e21 V m^-2 atomic unit of electric polarizablity 1.648 777 2536 e-41 0.000 000 0034 e-41 C^2 m^2 J^-1 atomic unit of electric potential 27.211 383 86 0.000 000 68 V atomic unit of electric quadrupole mom. 4.486 551 07 e-40 0.000 000 11 e-40 C m^2 atomic unit of energy 4.359 743 94 e-18 0.000 000 22 e-18 J atomic unit of force 8.238 722 06 e-8 0.000 000 41 e-8 N atomic unit of length 0.529 177 208 59 e-10 0.000 000 000 36 e-10 m atomic unit of mag. dipole mom. 1.854 801 830 e-23 0.000 000 046 e-23 J T^-1 atomic unit of mag. flux density 2.350 517 382 e5 0.000 000 059 e5 T atomic unit of magnetizability 7.891 036 433 e-29 0.000 000 027 e-29 J T^-2 atomic unit of mass 9.109 382 15 e-31 0.000 000 45 e-31 kg atomic unit of momentum 1.992 851 565 e-24 0.000 000 099 e-24 kg m s^-1 atomic unit of permittivity 1.112 650 056... e-10 (exact) F m^-1 atomic unit of time 2.418 884 326 505 e-17 0.000 000 000 016 e-17 s atomic unit of velocity 2.187 691 2541 e6 0.000 000 0015 e6 m s^-1 Avogadro constant 6.022 141 79 e23 0.000 000 30 e23 mol^-1 Bohr magneton 927.400 915 e-26 0.000 023 e-26 J T^-1 Bohr magneton in eV/T 5.788 381 7555 e-5 0.000 000 0079 e-5 eV T^-1 Bohr magneton in Hz/T 13.996 246 04 e9 0.000 000 35 e9 Hz T^-1 Bohr magneton in inverse meters per tesla 46.686 4515 0.000 0012 m^-1 T^-1 Bohr magneton in K/T 0.671 7131 0.000 0012 K T^-1 Bohr radius 0.529 177 208 59 e-10 0.000 000 000 36 e-10 m Boltzmann constant 1.380 6504 e-23 0.000 0024 e-23 J K^-1 Boltzmann constant in eV/K 8.617 343 e-5 0.000 015 e-5 eV K^-1 Boltzmann constant in Hz/K 2.083 6644 e10 0.000 0036 e10 Hz K^-1 Boltzmann constant in inverse meters per kelvin 69.503 56 0.000 12 m^-1 K^-1 characteristic impedance of vacuum 376.730 313 461... (exact) ohm classical electron radius 2.817 940 2894 e-15 0.000 000 0058 e-15 m Compton wavelength 2.426 310 2175 e-12 0.000 000 0033 e-12 m Compton wavelength over 2 pi 386.159 264 59 e-15 0.000 000 53 e-15 m conductance quantum 7.748 091 7004 e-5 0.000 000 0053 e-5 S conventional value of Josephson constant 483 597.9 e9 (exact) Hz V^-1 conventional value of von Klitzing constant 25 812.807 (exact) ohm Cu x unit 1.002 076 99 e-13 0.000 000 28 e-13 m deuteron-electron mag. mom. ratio -4.664 345 537 e-4 0.000 000 039 e-4 deuteron-electron mass ratio 3670.482 9654 0.000 0016 deuteron g factor 0.857 438 2308 0.000 000 0072 deuteron mag. mom. 0.433 073 465 e-26 0.000 000 011 e-26 J T^-1 deuteron mag. mom. to Bohr magneton ratio 0.466 975 4556 e-3 0.000 000 0039 e-3 deuteron mag. mom. to nuclear magneton ratio 0.857 438 2308 0.000 000 0072 deuteron mass 3.343 583 20 e-27 0.000 000 17 e-27 kg deuteron mass energy equivalent 3.005 062 72 e-10 0.000 000 15 e-10 J deuteron mass energy equivalent in MeV 1875.612 793 0.000 047 MeV deuteron mass in u 2.013 553 212 724 0.000 000 000 078 u deuteron molar mass 2.013 553 212 724 e-3 0.000 000 000 078 e-3 kg mol^-1 deuteron-neutron mag. mom. ratio -0.448 206 52 0.000 000 11 deuteron-proton mag. mom. ratio 0.307 012 2070 0.000 000 0024 deuteron-proton mass ratio 1.999 007 501 08 0.000 000 000 22 deuteron rms charge radius 2.1402 e-15 0.0028 e-15 m electric constant 8.854 187 817... e-12 (exact) F m^-1 electron charge to mass quotient -1.758 820 150 e11 0.000 000 044 e11 C kg^-1 electron-deuteron mag. mom. ratio -2143.923 498 0.000 018 electron-deuteron mass ratio 2.724 437 1093 e-4 0.000 000 0012 e-4 electron g factor -2.002 319 304 3622 0.000 000 000 0015 electron gyromag. ratio 1.760 859 770 e11 0.000 000 044 e11 s^-1 T^-1 electron gyromag. ratio over 2 pi 28 024.953 64 0.000 70 MHz T^-1 electron mag. mom. -928.476 377 e-26 0.000 023 e-26 J T^-1 electron mag. mom. anomaly 1.159 652 181 11 e-3 0.000 000 000 74 e-3 electron mag. mom. to Bohr magneton ratio -1.001 159 652 181 11 0.000 000 000 000 74 electron mag. mom. to nuclear magneton ratio -1838.281 970 92 0.000 000 80 electron mass 9.109 382 15 e-31 0.000 000 45 e-31 kg electron mass energy equivalent 8.187 104 38 e-14 0.000 000 41 e-14 J electron mass energy equivalent in MeV 0.510 998 910 0.000 000 013 MeV electron mass in u 5.485 799 0943 e-4 0.000 000 0023 e-4 u electron molar mass 5.485 799 0943 e-7 0.000 000 0023 e-7 kg mol^-1 electron-muon mag. mom. ratio 206.766 9877 0.000 0052 electron-muon mass ratio 4.836 331 71 e-3 0.000 000 12 e-3 electron-neutron mag. mom. ratio 960.920 50 0.000 23 electron-neutron mass ratio 5.438 673 4459 e-4 0.000 000 0033 e-4 electron-proton mag. mom. ratio -658.210 6848 0.000 0054 electron-proton mass ratio 5.446 170 2177 e-4 0.000 000 0024 e-4 electron-tau mass ratio 2.875 64 e-4 0.000 47 e-4 electron to alpha particle mass ratio 1.370 933 555 70 e-4 0.000 000 000 58 e-4 electron to shielded helion mag. mom. ratio 864.058 257 0.000 010 electron to shielded proton mag. mom. ratio -658.227 5971 0.000 0072 electron volt 1.602 176 487 e-19 0.000 000 040 e-19 J electron volt-atomic mass unit relationship 1.073 544 188 e-9 0.000 000 027 e-9 u electron volt-hartree relationship 3.674 932 540 e-2 0.000 000 092 e-2 E_h electron volt-hertz relationship 2.417 989 454 e14 0.000 000 060 e14 Hz electron volt-inverse meter relationship 8.065 544 65 e5 0.000 000 20 e5 m^-1 electron volt-joule relationship 1.602 176 487 e-19 0.000 000 040 e-19 J electron volt-kelvin relationship 1.160 4505 e4 0.000 0020 e4 K electron volt-kilogram relationship 1.782 661 758 e-36 0.000 000 044 e-36 kg elementary charge 1.602 176 487 e-19 0.000 000 040 e-19 C elementary charge over h 2.417 989 454 e14 0.000 000 060 e14 A J^-1 Faraday constant 96 485.3399 0.0024 C mol^-1 Faraday constant for conventional electric current 96 485.3401 0.0048 C_90 mol^-1 Fermi coupling constant 1.166 37 e-5 0.000 01 e-5 GeV^-2 fine-structure constant 7.297 352 5376 e-3 0.000 000 0050 e-3 first radiation constant 3.741 771 18 e-16 0.000 000 19 e-16 W m^2 first radiation constant for spectral radiance 1.191 042 759 e-16 0.000 000 059 e-16 W m^2 sr^-1 hartree-atomic mass unit relationship 2.921 262 2986 e-8 0.000 000 0042 e-8 u hartree-electron volt relationship 27.211 383 86 0.000 000 68 eV Hartree energy 4.359 743 94 e-18 0.000 000 22 e-18 J Hartree energy in eV 27.211 383 86 0.000 000 68 eV hartree-hertz relationship 6.579 683 920 722 e15 0.000 000 000 044 e15 Hz hartree-inverse meter relationship 2.194 746 313 705 e7 0.000 000 000 015 e7 m^-1 hartree-joule relationship 4.359 743 94 e-18 0.000 000 22 e-18 J hartree-kelvin relationship 3.157 7465 e5 0.000 0055 e5 K hartree-kilogram relationship 4.850 869 34 e-35 0.000 000 24 e-35 kg helion-electron mass ratio 5495.885 2765 0.000 0052 helion mass 5.006 411 92 e-27 0.000 000 25 e-27 kg helion mass energy equivalent 4.499 538 64 e-10 0.000 000 22 e-10 J helion mass energy equivalent in MeV 2808.391 383 0.000 070 MeV helion mass in u 3.014 932 2473 0.000 000 0026 u helion molar mass 3.014 932 2473 e-3 0.000 000 0026 e-3 kg mol^-1 helion-proton mass ratio 2.993 152 6713 0.000 000 0026 hertz-atomic mass unit relationship 4.439 821 6294 e-24 0.000 000 0064 e-24 u hertz-electron volt relationship 4.135 667 33 e-15 0.000 000 10 e-15 eV hertz-hartree relationship 1.519 829 846 006 e-16 0.000 000 000 010 e-16 E_h hertz-inverse meter relationship 3.335 640 951... e-9 (exact) m^-1 hertz-joule relationship 6.626 068 96 e-34 0.000 000 33 e-34 J hertz-kelvin relationship 4.799 2374 e-11 0.000 0084 e-11 K hertz-kilogram relationship 7.372 496 00 e-51 0.000 000 37 e-51 kg inverse fine-structure constant 137.035 999 679 0.000 000 094 inverse meter-atomic mass unit relationship 1.331 025 0394 e-15 0.000 000 0019 e-15 u inverse meter-electron volt relationship 1.239 841 875 e-6 0.000 000 031 e-6 eV inverse meter-hartree relationship 4.556 335 252 760 e-8 0.000 000 000 030 e-8 E_h inverse meter-hertz relationship 299 792 458 (exact) Hz inverse meter-joule relationship 1.986 445 501 e-25 0.000 000 099 e-25 J inverse meter-kelvin relationship 1.438 7752 e-2 0.000 0025 e-2 K inverse meter-kilogram relationship 2.210 218 70 e-42 0.000 000 11 e-42 kg inverse of conductance quantum 12 906.403 7787 0.000 0088 ohm Josephson constant 483 597.891 e9 0.012 e9 Hz V^-1 joule-atomic mass unit relationship 6.700 536 41 e9 0.000 000 33 e9 u joule-electron volt relationship 6.241 509 65 e18 0.000 000 16 e18 eV joule-hartree relationship 2.293 712 69 e17 0.000 000 11 e17 E_h joule-hertz relationship 1.509 190 450 e33 0.000 000 075 e33 Hz joule-inverse meter relationship 5.034 117 47 e24 0.000 000 25 e24 m^-1 joule-kelvin relationship 7.242 963 e22 0.000 013 e22 K joule-kilogram relationship 1.112 650 056... e-17 (exact) kg kelvin-atomic mass unit relationship 9.251 098 e-14 0.000 016 e-14 u kelvin-electron volt relationship 8.617 343 e-5 0.000 015 e-5 eV kelvin-hartree relationship 3.166 8153 e-6 0.000 0055 e-6 E_h kelvin-hertz relationship 2.083 6644 e10 0.000 0036 e10 Hz kelvin-inverse meter relationship 69.503 56 0.000 12 m^-1 kelvin-joule relationship 1.380 6504 e-23 0.000 0024 e-23 J kelvin-kilogram relationship 1.536 1807 e-40 0.000 0027 e-40 kg kilogram-atomic mass unit relationship 6.022 141 79 e26 0.000 000 30 e26 u kilogram-electron volt relationship 5.609 589 12 e35 0.000 000 14 e35 eV kilogram-hartree relationship 2.061 486 16 e34 0.000 000 10 e34 E_h kilogram-hertz relationship 1.356 392 733 e50 0.000 000 068 e50 Hz kilogram-inverse meter relationship 4.524 439 15 e41 0.000 000 23 e41 m^-1 kilogram-joule relationship 8.987 551 787... e16 (exact) J kilogram-kelvin relationship 6.509 651 e39 0.000 011 e39 K lattice parameter of silicon 543.102 064 e-12 0.000 014 e-12 m Loschmidt constant (273.15 K, 101.325 kPa) 2.686 7774 e25 0.000 0047 e25 m^-3 mag. constant 12.566 370 614... e-7 (exact) N A^-2 mag. flux quantum 2.067 833 667 e-15 0.000 000 052 e-15 Wb molar gas constant 8.314 472 0.000 015 J mol^-1 K^-1 molar mass constant 1 e-3 (exact) kg mol^-1 molar mass of carbon-12 12 e-3 (exact) kg mol^-1 molar Planck constant 3.990 312 6821 e-10 0.000 000 0057 e-10 J s mol^-1 molar Planck constant times c 0.119 626 564 72 0.000 000 000 17 J m mol^-1 molar volume of ideal gas (273.15 K, 100 kPa) 22.710 981 e-3 0.000 040 e-3 m^3 mol^-1 molar volume of ideal gas (273.15 K, 101.325 kPa) 22.413 996 e-3 0.000 039 e-3 m^3 mol^-1 molar volume of silicon 12.058 8349 e-6 0.000 0011 e-6 m^3 mol^-1 Mo x unit 1.002 099 55 e-13 0.000 000 53 e-13 m muon Compton wavelength 11.734 441 04 e-15 0.000 000 30 e-15 m muon Compton wavelength over 2 pi 1.867 594 295 e-15 0.000 000 047 e-15 m muon-electron mass ratio 206.768 2823 0.000 0052 muon g factor -2.002 331 8414 0.000 000 0012 muon mag. mom. -4.490 447 86 e-26 0.000 000 16 e-26 J T^-1 muon mag. mom. anomaly 1.165 920 69 e-3 0.000 000 60 e-3 muon mag. mom. to Bohr magneton ratio -4.841 970 49 e-3 0.000 000 12 e-3 muon mag. mom. to nuclear magneton ratio -8.890 597 05 0.000 000 23 muon mass 1.883 531 30 e-28 0.000 000 11 e-28 kg muon mass energy equivalent 1.692 833 510 e-11 0.000 000 095 e-11 J muon mass energy equivalent in MeV 105.658 3668 0.000 0038 MeV muon mass in u 0.113 428 9256 0.000 000 0029 u muon molar mass 0.113 428 9256 e-3 0.000 000 0029 e-3 kg mol^-1 muon-neutron mass ratio 0.112 454 5167 0.000 000 0029 muon-proton mag. mom. ratio -3.183 345 137 0.000 000 085 muon-proton mass ratio 0.112 609 5261 0.000 000 0029 muon-tau mass ratio 5.945 92 e-2 0.000 97 e-2 natural unit of action 1.054 571 628 e-34 0.000 000 053 e-34 J s natural unit of action in eV s 6.582 118 99 e-16 0.000 000 16 e-16 eV s natural unit of energy 8.187 104 38 e-14 0.000 000 41 e-14 J natural unit of energy in MeV 0.510 998 910 0.000 000 013 MeV natural unit of length 386.159 264 59 e-15 0.000 000 53 e-15 m natural unit of mass 9.109 382 15 e-31 0.000 000 45 e-31 kg natural unit of momentum 2.730 924 06 e-22 0.000 000 14 e-22 kg m s^-1 natural unit of momentum in MeV/c 0.510 998 910 0.000 000 013 MeV/c natural unit of time 1.288 088 6570 e-21 0.000 000 0018 e-21 s natural unit of velocity 299 792 458 (exact) m s^-1 neutron Compton wavelength 1.319 590 8951 e-15 0.000 000 0020 e-15 m neutron Compton wavelength over 2 pi 0.210 019 413 82 e-15 0.000 000 000 31 e-15 m neutron-electron mag. mom. ratio 1.040 668 82 e-3 0.000 000 25 e-3 neutron-electron mass ratio 1838.683 6605 0.000 0011 neutron g factor -3.826 085 45 0.000 000 90 neutron gyromag. ratio 1.832 471 85 e8 0.000 000 43 e8 s^-1 T^-1 neutron gyromag. ratio over 2 pi 29.164 6954 0.000 0069 MHz T^-1 neutron mag. mom. -0.966 236 41 e-26 0.000 000 23 e-26 J T^-1 neutron mag. mom. to Bohr magneton ratio -1.041 875 63 e-3 0.000 000 25 e-3 neutron mag. mom. to nuclear magneton ratio -1.913 042 73 0.000 000 45 neutron mass 1.674 927 211 e-27 0.000 000 084 e-27 kg neutron mass energy equivalent 1.505 349 505 e-10 0.000 000 075 e-10 J neutron mass energy equivalent in MeV 939.565 346 0.000 023 MeV neutron mass in u 1.008 664 915 97 0.000 000 000 43 u neutron molar mass 1.008 664 915 97 e-3 0.000 000 000 43 e-3 kg mol^-1 neutron-muon mass ratio 8.892 484 09 0.000 000 23 neutron-proton mag. mom. ratio -0.684 979 34 0.000 000 16 neutron-proton mass ratio 1.001 378 419 18 0.000 000 000 46 neutron-tau mass ratio 0.528 740 0.000 086 neutron to shielded proton mag. mom. ratio -0.684 996 94 0.000 000 16 Newtonian constant of gravitation 6.674 28 e-11 0.000 67 e-11 m^3 kg^-1 s^-2 Newtonian constant of gravitation over h-bar c 6.708 81 e-39 0.000 67 e-39 (GeV/c^2)^-2 nuclear magneton 5.050 783 24 e-27 0.000 000 13 e-27 J T^-1 nuclear magneton in eV/T 3.152 451 2326 e-8 0.000 000 0045 e-8 eV T^-1 nuclear magneton in inverse meters per tesla 2.542 623 616 e-2 0.000 000 064 e-2 m^-1 T^-1 nuclear magneton in K/T 3.658 2637 e-4 0.000 0064 e-4 K T^-1 nuclear magneton in MHz/T 7.622 593 84 0.000 000 19 MHz T^-1 Planck constant 6.626 068 96 e-34 0.000 000 33 e-34 J s Planck constant in eV s 4.135 667 33 e-15 0.000 000 10 e-15 eV s Planck constant over 2 pi 1.054 571 628 e-34 0.000 000 053 e-34 J s Planck constant over 2 pi in eV s 6.582 118 99 e-16 0.000 000 16 e-16 eV s Planck constant over 2 pi times c in MeV fm 197.326 9631 0.000 0049 MeV fm Planck length 1.616 252 e-35 0.000 081 e-35 m Planck mass 2.176 44 e-8 0.000 11 e-8 kg Planck mass energy equivalent in GeV 1.220 892 e19 0.000 061 e19 GeV Planck temperature 1.416 785 e32 0.000 071 e32 K Planck time 5.391 24 e-44 0.000 27 e-44 s proton charge to mass quotient 9.578 833 92 e7 0.000 000 24 e7 C kg^-1 proton Compton wavelength 1.321 409 8446 e-15 0.000 000 0019 e-15 m proton Compton wavelength over 2 pi 0.210 308 908 61 e-15 0.000 000 000 30 e-15 m proton-electron mass ratio 1836.152 672 47 0.000 000 80 proton g factor 5.585 694 713 0.000 000 046 proton gyromag. ratio 2.675 222 099 e8 0.000 000 070 e8 s^-1 T^-1 proton gyromag. ratio over 2 pi 42.577 4821 0.000 0011 MHz T^-1 proton mag. mom. 1.410 606 662 e-26 0.000 000 037 e-26 J T^-1 proton mag. mom. to Bohr magneton ratio 1.521 032 209 e-3 0.000 000 012 e-3 proton mag. mom. to nuclear magneton ratio 2.792 847 356 0.000 000 023 proton mag. shielding correction 25.694 e-6 0.014 e-6 proton mass 1.672 621 637 e-27 0.000 000 083 e-27 kg proton mass energy equivalent 1.503 277 359 e-10 0.000 000 075 e-10 J proton mass energy equivalent in MeV 938.272 013 0.000 023 MeV proton mass in u 1.007 276 466 77 0.000 000 000 10 u proton molar mass 1.007 276 466 77 e-3 0.000 000 000 10 e-3 kg mol^-1 proton-muon mass ratio 8.880 243 39 0.000 000 23 proton-neutron mag. mom. ratio -1.459 898 06 0.000 000 34 proton-neutron mass ratio 0.998 623 478 24 0.000 000 000 46 proton rms charge radius 0.8768 e-15 0.0069 e-15 m proton-tau mass ratio 0.528 012 0.000 086 quantum of circulation 3.636 947 5199 e-4 0.000 000 0050 e-4 m^2 s^-1 quantum of circulation times 2 7.273 895 040 e-4 0.000 000 010 e-4 m^2 s^-1 Rydberg constant 10 973 731.568 527 0.000 073 m^-1 Rydberg constant times c in Hz 3.289 841 960 361 e15 0.000 000 000 022 e15 Hz Rydberg constant times hc in eV 13.605 691 93 0.000 000 34 eV Rydberg constant times hc in J 2.179 871 97 e-18 0.000 000 11 e-18 J Sackur-Tetrode constant (1 K, 100 kPa) -1.151 7047 0.000 0044 Sackur-Tetrode constant (1 K, 101.325 kPa) -1.164 8677 0.000 0044 second radiation constant 1.438 7752 e-2 0.000 0025 e-2 m K shielded helion gyromag. ratio 2.037 894 730 e8 0.000 000 056 e8 s^-1 T^-1 shielded helion gyromag. ratio over 2 pi 32.434 101 98 0.000 000 90 MHz T^-1 shielded helion mag. mom. -1.074 552 982 e-26 0.000 000 030 e-26 J T^-1 shielded helion mag. mom. to Bohr magneton ratio -1.158 671 471 e-3 0.000 000 014 e-3 shielded helion mag. mom. to nuclear magneton ratio -2.127 497 718 0.000 000 025 shielded helion to proton mag. mom. ratio -0.761 766 558 0.000 000 011 shielded helion to shielded proton mag. mom. ratio -0.761 786 1313 0.000 000 0033 shielded proton gyromag. ratio 2.675 153 362 e8 0.000 000 073 e8 s^-1 T^-1 shielded proton gyromag. ratio over 2 pi 42.576 3881 0.000 0012 MHz T^-1 shielded proton mag. mom. 1.410 570 419 e-26 0.000 000 038 e-26 J T^-1 shielded proton mag. mom. to Bohr magneton ratio 1.520 993 128 e-3 0.000 000 017 e-3 shielded proton mag. mom. to nuclear magneton ratio 2.792 775 598 0.000 000 030 speed of light in vacuum 299 792 458 (exact) m s^-1 standard acceleration of gravity 9.806 65 (exact) m s^-2 standard atmosphere 101 325 (exact) Pa Stefan-Boltzmann constant 5.670 400 e-8 0.000 040 e-8 W m^-2 K^-4 tau Compton wavelength 0.697 72 e-15 0.000 11 e-15 m tau Compton wavelength over 2 pi 0.111 046 e-15 0.000 018 e-15 m tau-electron mass ratio 3477.48 0.57 tau mass 3.167 77 e-27 0.000 52 e-27 kg tau mass energy equivalent 2.847 05 e-10 0.000 46 e-10 J tau mass energy equivalent in MeV 1776.99 0.29 MeV tau mass in u 1.907 68 0.000 31 u tau molar mass 1.907 68 e-3 0.000 31 e-3 kg mol^-1 tau-muon mass ratio 16.8183 0.0027 tau-neutron mass ratio 1.891 29 0.000 31 tau-proton mass ratio 1.893 90 0.000 31 Thomson cross section 0.665 245 8558 e-28 0.000 000 0027 e-28 m^2 triton-electron mag. mom. ratio -1.620 514 423 e-3 0.000 000 021 e-3 triton-electron mass ratio 5496.921 5269 0.000 0051 triton g factor 5.957 924 896 0.000 000 076 triton mag. mom. 1.504 609 361 e-26 0.000 000 042 e-26 J T^-1 triton mag. mom. to Bohr magneton ratio 1.622 393 657 e-3 0.000 000 021 e-3 triton mag. mom. to nuclear magneton ratio 2.978 962 448 0.000 000 038 triton mass 5.007 355 88 e-27 0.000 000 25 e-27 kg triton mass energy equivalent 4.500 387 03 e-10 0.000 000 22 e-10 J triton mass energy equivalent in MeV 2808.920 906 0.000 070 MeV triton mass in u 3.015 500 7134 0.000 000 0025 u triton molar mass 3.015 500 7134 e-3 0.000 000 0025 e-3 kg mol^-1 triton-neutron mag. mom. ratio -1.557 185 53 0.000 000 37 triton-proton mag. mom. ratio 1.066 639 908 0.000 000 010 triton-proton mass ratio 2.993 717 0309 0.000 000 0025 unified atomic mass unit 1.660 538 782 e-27 0.000 000 083 e-27 kg von Klitzing constant 25 812.807 557 0.000 018 ohm weak mixing angle 0.222 55 0.000 56 Wien frequency displacement law constant 5.878 933 e10 0.000 010 e10 Hz K^-1 Wien wavelength displacement law constant 2.897 7685 e-3 0.000 0051 e-3 m K