# Modern Physics/Constants of Nature

This is a brief listing of some constant values that are used in this book. Constants are currently listed in no particular order.

Constant Name | Definition |
---|---|

Absolute zero temperature | 0 K = −273.15 °C |

Speed of light in vacuum | c = 2.99792458 × 10^{8} m·s^{-1} |

Newtonian constant of gravitation | G = 6.6742 × 10^{−11} m^{3}·kg^{-1} s^{-2} |

Planck constant | h = 6.6260693 × 10^{−34} J·Hz^{-1} = 4.136 × 10^{-15} eV·s; |

Planck constant over | = 1.05457148 × 10^{−34} J·s |

Elementary charge | e = 1.60217653 × 10^{−19} C |

Avogadro constant | N_{A} = 6.0221415 × 10^{23} mol^{-1} |

Constant in Coulomb's law | K = 8.988 × 10^{9} N·m^{2}·kg^{-2} |

Boltzmann's constant | k = 1.3806505 × 10^{−23} J K^{-1} |

Stefan-Boltzmann constant | σ = 5.670400 × 10^{−8} W·m^{-2}·K^{-4} |

Unified atomic mass unit | 1 u = 1.66056×10^{−27} kg |

Bohr radius | a = 5.292 × 10_{0}^{−11} m |

Electron radius | r = 2.81792 × 10_{e}^{-15} |

Molar gas constant | R = 8.314472 J·mol^{-1}·K^{-1} |

Molar Volume | V = 22.41383 m_{mol}^{3}·kmol^{-1} |

Mass of an electron | m_{e} = 9.1093897 × 10^{-31} kg |

Mass of a proton | m_{p} = 1.6726231 × 10^{-27} kg |

Mass of a neutron | m_{n} = 1.6749286 × 10^{-27} kg |

Permeability of vacuum | μ_{0} = 4π × 10^{−7}T^{2}·m^{3}·J^{-1} = 12.566370614 × 10^{−7} T^{2}·m^{3}·J^{-1} |

Permittivity of vacuum | ε_{0} = 1/(μ_{0}c^{2}) = 8.854187817 × 10^{−12} C^{2}·J^{-1}·m^{-1} |

Fine structure constant | α = e^{2}/(2ε_{0}hc) = 1/137.0359895 = 7.2974 × 10^{-3} |

Thomson cross-section | σ_{e} = 6.652 × 10^{−29} m^{2} |

Some values from the 2002 CODATA recommended values of the Fundamental Physical Constants. See Constants Information at NIST.