physical constant
physical quantity that is generally believed to be both universal in nature and constant in time
Angstrom star
unit of length; equals 1.000 014 98(90) angstrom
standard acceleration of free fall
standard gravitational acceleration on Earth's surface
speed of light in vacuum
speed of electromagnetic waves in vacuum
fine-structure constant
physical constant quantifying the strength of the electromagnetic interaction between elementary charged particles
Bohr magneton
unit of magnetic moment (approx. 9.2 J/T); the magnetic dipole moment of an electron orbiting an atom with angular momentum ℏ in the Bohr model
nuclear magneton
physical constant of magnetic moment
classical electron radius
physical constant providing length scale to interatomic interactions