|
Symbol
|
Value[1] (SI units)
|
Relative Standard Uncertainty
|
magnetic constant (vacuum permeability)
|
|
4π × 10−7 N·A−2 = 1.256 637 061... × 10−6 N·A−2
|
defined
|
electric constant (vacuum permittivity)
|
|
8.854 187 817... × 10−12 F·m−1
|
defined
|
characteristic impedance of vacuum
|
|
376.730 313 461... Ω
|
defined
|
Coulomb's constant
|
|
8.987 551 787... × 109 N·m²·C−2
|
defined
|
elementary charge
|
|
1.602 176 487(40) × 10−19 C
|
2.5 × 10−8
|
Bohr magneton
|
|
927.400 915(23) × 10−26 J·T−1
|
2.5 × 10−8
|
conductance quantum
|
|
7.748 091 7004(53) × 10−5 S
|
6.8 × 10−10
|
inverse conductance quantum
|
|
12 906.403 7787(88) Ω
|
6.8 × 10−10
|
Josephson constant
|
|
4.835 978 91(12) × 1014 Hz·V−1
|
2.5 × 10−8
|
magnetic flux quantum
|
|
2.067 833 667(52) × 10−15 Wb
|
2.5 × 10−8
|
nuclear magneton
|
|
5.050 783 43(43) × 10−27 J·T−1
|
8.6 × 10−8
|
von Klitzing constant
|
|
25 812.807 557(18) Ω
|
6.8 × 10−10
|