Symbol R. A constant that occurs in the formulae for atomic spectra and is related to the binding energy between an electron and a nucleus. It is connected to other constants by the relationship R=μ‎₀²me⁴c³/8h³, where μ‎₀ is the magnetic constant (see permeability), m and e are the mass and charge of an electron, c is the speed of light, and h is the Planck constant. It has the value 1.097 × 10⁷ m⁻¹. It is named after the Swedish physicist Johannes Robert Rydberg (1854–1919), who in 1890 developed a formula for the spectrum of atoms, which is particularly simple in the case of hydrogen atoms.