keynamesymbolSI value, unit
alphafine-structure constant = e^2/(4 pi eps_0 hbar c)alpha7.297 352 5698(24) e-3
alpha-1inverse fine-structure constant = 4 pi eps_0 hbar c/e^2137.035 999 074(44)
amuunified atomic mass unit = 1/12 m(12C)u1.660 538 921(73) e-27 kg
avogadroAvogadro constantN_A6.022 141 29(27) e23 mol^-1
bohrmagnBohr magneton = e hbar/(2 m_e)mu_B9.274 009 68(20) e-24 J/T
bohrradiusBohr radius = 4 pi eps_0 hbar^2/(m_e e^2)a_00.529 177 210 92(17) e-10 m
boltzmannBoltzmann constantk_B1.380 6488(13) e-23 J/K
charge-eelementary chargee1.602 176 565(35) e-19 C
conduct-quconductance quantum = 2 e^2/hG_07.748 091 7346(25) e-5 S
diracDirac's constant = h/(2 pi)hbar1.054 571 726(47) e-34 J s
elec-constdielectric permittivity of vacuumeps_08.854 187 817... e-12 F/m
faradayFaraday constant = N_A eF96 485.3365(21) C/mol
gasmolar gas constant = N_A k_BR8.314 4621(75) J mol^-1 K^-1
gfactor-eelectron g-factorg_e-2.002 319 304 361 53(53)
gfactor-pproton g-factorg_p5.585 694 713(46)
gravitNewton constant of gravitationG6.673 84(80) e-11 m^3 kg^-1 s^-2
gyromagratio-pproton gyromagnetic ratiogamma_p2.675 222 005(63) e8 s^-1 T^-1
josephsonJosephson constant = 2 e/hK_J4.835 978 70(11) e14 Hz/V
lightvelvelocity of light in vacuumc299 792 458(ex) m/s
magflux-qumagnetic flux quantum = h/(2 e)Phi_02.067 833 758(46) Wb
magn-constmagnetic permeability of vacuummu_01.256 637 061... e-6 N A^-2
magnmom-eelectron magnetic momentmu_e-9.284 764 30(21) e-24 J/T
magnmom-pproton magnetic momentmu_p1.410 606 743(33) e-26 J/T
magres-pmagnetic resonance frequency proton = gamma_p/(2*pi)42.577 4806(10) MHz/T
mass-ddeuteron massm_d3.343 583 48(15) e-27 kg
mass-d/udeuteron mass in um_d_u2.013 553 212 712(77) u
mass-eelectron massm_e9.109 382 91(40) e-31 kg
mass-e/uelectron mass in um_e_u5.485 799 0946(22) u
mass-mumuon massm_m1.883 531 475(96) e-28 kg
mass-mu/umuon mass in um_m_u0.113 428 9267(29) u
mass-nneutron massm_n1.674 927 351(74) e-27 kg
mass-n/uneutron mass in um_n_u1.008 664 916 00(43) u
mass-pproton massm_p1.672 621 777(74) e-27 kg
mass-p/uproton mass in um_p_u1.007 276 466 812(90) u
nuclmagnnuclear magneton = e hbar/(2 m_p)mu_N5.050 783 53(11) e-27 J/T
planckPlanck's constanth6.626 069 57(29) e-34 J s
ratio-me/mpelectron/proton mass ratioratio_memp5.446 170 2178(22) e-4
ratio-mp/meproton/electron mass ratioratio_mpme1836.152 672 45(75)
rydbergRydberg constant = alpha^2 m_e c/(2 h)R_infty10 973 731.568 539(55) m^-1
stefan-boltzmStefan-Boltzmann constant = pi^2 k^4/(60 hbar^3 c^2)sigma5.670 373(21) e-8 W m^-2 K^-4