Physics Constant
Fundamental
Constants
Name
|
Symbol
|
Value
|
Speed
of light in vacuum
|
c
|
2.99792458
× 108 m·s-1
|
Elementary
charge
|
e
|
1.602176487(40)
× 10–19 C
|
Universal
gravitational constant
|
G
|
6.67428(67)
× 10–11 m3·kg-1·s-2
|
Planck’s
constant
|
h
|
6.62606896(33)
× 10–34 J·s
|
Boltzmann’s
constant
|
kB
|
1.3806504(24)
× 10–23 J·K-1
|
Avogadro’s
number
|
NA
|
6.02214179(30)
× 1023 mol–1
|
Universal
gas constant
|
R
|
8.314472(15)
J·mol-1·K-1
|
Mass
of an electron
|
me
|
9.10938215(45)
× 10–31 kg
|
Mass
of a proton
|
mp
|
1.672621637(83)
× 10–27 kg
|
Mass
of a neutron
|
mn
|
1.674927211(84)
× 10–27 kg
|
Magnetic
permeability of free space
|
μ0
|
4π × 10–7
N·A-2
|
Electric
permittivity of free space
|
ε0
= 1/( μ0c2)
|
8.854187817...
×10–12 N·A-2
|
Stefan-Boltzmann
constant
|
σ
|
5.760400(40)
× 10–8 W·m-2·K-4
|
Other Useful Constants
Name
|
Symbol
|
Value
|
Standard
acceleration due to gravity
|
g
|
9.81
m·s–2
|
Standard
atmospheric pressure at 20 °C
|
atm
|
1.01325 × 105 Pa
|
Volume
of ideal gas at 0 °C and 1 atm
|
22.413996(39)
liter·mol-1
|
|
Mechanical
equivalent of heat
|
4.186 J·cal-1
|
|
Atomic
mass unit
|
u
|
1.660538782(83)
kg
|
Electron-volt
|
eV
|
1.602176487(40)
× 10–19 J
|
Atomic
mass unit energy equivalent
|
uc2
|
931.494028(23)
MeV
|
Electron
mass energy equivalent
|
mec2
|
0.510998910(13)
MeV
|
Proton
mass energy equivalent
|
mpc2
|
938.272013(23)
MeV
|
Neutron
mass energy equivalent
|
mnc2
|
939.565346(23)
MeV
|
Planck’s
constant divided by 2π
|
ħ
|
1.054571628(53)
× 10–34 J·s
|
Planck’s
constant divided by 2π times c
|
ħc
|
197.3269631(49)
Me·V·fm
|
Bohr
radius
|
a0
|
0.52917720859(36)
× 10–10 m
|
Source: National Institute of Standards and
Technology, http://physics.nist.gov/constants. The numbers in parentheses show
the uncertainty in the final digits of the quoted number. For example,
6.67428(67) means 6.67428 ± 0.00067. Values shown without uncertainties
are exact.
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