Physical Constants
Physical constants are fundamental, universal constants that represent physical quantities. COMSOL Multiphysics includes the most widely used physical constants as built-in constants.
Table 5-8
lists all supported physical constants with their names, symbol (variable name), value, and SI unit. The values are taken from Ref. 1 and include the SI unit.
Table 5-8:
Physical Constants.
Name
Symbol
Value
Acceleration of gravity
g_const
9.80665[m/s^2]
Avogadro constant
N_A_const
6.02214076e23[1/mol]
Bohr radius
a0_const
4*pi*epsilon0_const*hbar_const^2/(me_const*e_const^2) (m) (5.29177...e-11[m])
Boltzmann constant
k_B_const
1.380649e-23[J/K]
Characteristic impedance of vacuum (impedance of free space)
Z0_const
mu0_const*c_const (ohm) (376.730313461...[ohm])
Electron mass
me_const
9.10938356e-31[kg]
Elementary charge
e_const
1.602176634e-19[C]
Faraday constant
F_const
96485.33289[C/mol]
Fine-structure constant
alpha_const
7.2973525664e-3
Gravitational constant
G_const
6.67408e-11[m^3/(kg*s^2)]
Molar volume of ideal gas (at 273.15 K and 1 atm)
V_m_const
22.413962e-3[m^3/mol]
Neutron mass
mn_const
1.674927471e-27[kg]
Permeability of vacuum (magnetic constant)
mu0_const
2*alpha_const*h_const/c_const/e_const/e_const (H/m) (1.256637...e?6[N/A^2])
Permittivity of vacuum (electric constant)
epsilon0_const
1/mu0_const/c_const/c_const (F/m) (8.854187...e?12[F/m])
Planck’s constant
h_const
6.62607015e-34[J*s]
Planck’s constant over 2 pi
hbar_const
1.05457180e-34[J*s]
Proton mass
mp_const
1.672621898e-27[kg]
Speed of light in vacuum
c_const
299792458[m/s]
Stefan-Boltzmann constant
sigma_const
5.670367e-8[W/(m^2*K^4)]
Universal gas constant (molar gas constant)
R_const
8.3144598[J/(mol*K)]
Wien displacement law constant
b_const
2.8977729e-3[m*K]
Reference
1.
The NIST Reference on Constants, Units, and Uncertainty
,
http://physics.nist.gov/cuu/Constants/index.html