### 8.2.2 Constants Library

The physical constants are in the Phys menu, Constant sub-menu. The following table gives the Constants Library :

Name | Description
_NA_ | Avogadro’s number
_k_ | Boltzmann constant
_Vm_ | Molar volume
_R_ | Universal gas constant
_StdT_ | Standard temperature
_StdP_ | Standard pressure
_sigma_ | Stefan-Boltzmann constant
_c_ | Speed of light in vacuum
_epsilon0_ | Permitivity of vacuum
_mu0_ | Permeability of vacuum
_g_ | Acceleration of gravity
_G_ | Gravitational constant
_h_ | Planck’s constant
_hbar_ | Dirac’s constant
_q_ | Electron charge
_me_ | Electron rest mass
_qme_ | q/me (Electron charge/mass)
_mp_ | Proton rest mass
_mpme_ | mp/me (proton mass/electron mass)
_alpha_ | Fine structure constant
_phi_ | Magnetic flux quantum
_F_ | Faraday constant
_Rinfinity_ | Rydberg constant
_a0_ | Bohr radius
_muB_ | Bohr magneton
_muN_ | Nuclear magneton
_lambda0_ | Photon wavelength (ch/e)
_f0_ | Photon frequency (e/h)
_lambdac_ | Compton wavelength
_rad_ | 1 radian
_twopi_ | 2*pi radians
_angl_ | 180 degrees angle
_c3_ | Wien displacement constant
_kq_ | k/q (Boltzmann/electron charge)
_epsilon0q_ | epsilon0/q (permitivity /electron charge)
_qepsilon0_ | q*epsilon0 (electron charge *permitivity)
_epsilonsi_ | Silicium dielectric constant
_epsilonox_ | Bioxyd of silicium dielectric constant
_I0_ | Reference intensity

To have the value of a constant, input the constant name in the command line of Xcas and evaluate with enter (don’t forget to put _ at the beginning and at the end of the constant name).