Physical Constants
Reference
| symbol | name | value | |||
|---|---|---|---|---|---|
| c | speed of light in a vacuum |
299,792,458 m/s | |||
| G | gravitational constant |
6.67430 × 10−11 N m2/kg2 | |||
| h | Planck constant |
6.626 070 15 × 10−34 J s 4.135 667 696 × 10−15 eV s |
|||
| hc | h c |
1.986 445 857 × 10−25 J m 1239.841 984 eV nm |
|||
|
h bar, reduced Planck constant, Dirac constant |
1.054 571 817 × 10−34 J s 6.582 119 569 × 10−16 eV s |
|||
| ΔνCs | hyperfine transition of 133Cs |
9,192,631,770 Hz | |||
| e | elementary charge |
1.602 176 634 × 10−19 C | |||
| ε0 | electric constant, permitivitty of free space, vacuum permitivitty |
8.854 187 818 8 × 10−12 C2/N m2 | |||
| μ0 | magnetic constant, permeability of free space, vacuum permeability |
1.256 637 061 27 × 10−6 T m/A | |||
| NA | Avogadro constant |
6.022 140 76 × 1023 1/mol | |||
| k | Boltzmann constant |
1.380 649 × 10−23 J/K | |||
| R = NAk | molar gas constant |
8.314 462 618 J/mol K | |||
|
Stefan-Boltzmann constant |
5.670 374 419 × 10−8 W/m2K4 | |||
| b, b′ | Wien displacement constant |
2897.771 955 μm K 58.789 257 57 GHz/K |
|||
| mu | atomic mass constant atomic mass unit unified atomic mass unit |
1.660 539 068 92 × 10−27 kg 931.494 103 72 MeV/c2 1 u |
|||
| me | electron mass |
9.109 383 701 5 × 10−31 kg 0.510 998 950 00 MeV/c2 5.485 799 090 65 × 10−4 u |
|||
| mp | proton mass |
1.672 621 923 69 × 10−27 kg 938.272 088 16 MeV/c2 1.007 276 466 621 u |
|||
| mn | neutron mass |
1.674 927 498 0 × 10−27 kg 939.565 420 5 MeV/c2 1.008 664 916 0 u |
|||
| Kcd | luminous efficacy |
683 lm/W | |||
| H0 | hubble constant* |
69.3 km/s/Mpc 2.25 × 10−18 1/s |