 
 
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_ | Permittivity 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/masse) | 
| _mp_ | Proton rest mass | 
| _mpme_ | mp/me (proton masse/electron masse) | 
| _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 valid with enter (don’t forget to put _ at the begining and at the end of the constant name).
 
