15 Constants

Values below are CODATA 2018 / SI exact definitions where applicable.

15.1 Electromagnetism

Symbol Name Value
\(e\) Elementary charge \(1.602\,176\,634 \times 10^{-19}\,\mathrm{C}\) (exact)
\(\varepsilon_0\) Vacuum permittivity \(8.854\,187\,8128(13) \times 10^{-12}\,\mathrm{F/m}\)
\(\mu_0\) Vacuum permeability \(1.256\,637\,062\,12(19) \times 10^{-6}\,\mathrm{N/A^{2}}\)
\(k = \dfrac{1}{4\pi\varepsilon_0}\) Coulomb constant \(8.987\,551\,7923(14) \times 10^{9}\,\mathrm{N\cdot m^{2}/C^{2}}\)

15.2 Special Relativity

Symbol Name Value
\(c\) Speed of light in vacuum \(299\,792\,458\,\mathrm{m/s}\) (exact)
\(m_{\mathrm{e}}c^{2}\) Electron rest energy \(0.510\,998\,950\,00(15)\,\mathrm{MeV}\)
\(m_{\mathrm{p}}c^{2}\) Proton rest energy \(938.272\,088\,16(29)\,\mathrm{MeV}\)

15.3 Quantum Mechanics

Symbol Name Value
\(h\) Planck constant \(6.626\,070\,15 \times 10^{-34}\,\mathrm{J\cdot s}\) (exact)
\(\hbar = h/(2\pi)\) Reduced Planck constant \(1.054\,571\,817\ldots \times 10^{-34}\,\mathrm{J\cdot s}\) (exact)
\(e\mathrm{V}\) Electronvolt \(1.602\,176\,634 \times 10^{-19}\,\mathrm{J}\) (exact)
\(hc\) Planck energy–length product \(1.239\,841\,984\ldots \times 10^{-6}\,\mathrm{eV\cdot m}\)
\(\hbar c\) Reduced Planck energy–length product \(197.326\,980\,4\ldots\,\mathrm{MeV\cdot fm}\)
\(R_{\infty}\) Rydberg constant \(1.097\,373\,156\,8160(21) \times 10^{7}\,\mathrm{m^{-1}}\)
\(hcR_{\infty}\) Rydberg energy \(13.605\,693\,122\,994(26)\,\mathrm{eV}\)
\(E_{\mathrm{h}}\) Hartree energy \(27.211\,386\,245\,988(53)\,\mathrm{eV}\)
\(E_1 = -hcR_{\infty}\) Hydrogen ground-state energy \(-13.605\,693\,122\,994(26)\,\mathrm{eV}\)
\(\alpha\) Fine-structure constant \(7.297\,352\,5693(11) \times 10^{-3}\)
\(a_0\) Bohr radius \(5.291\,772\,109\,03(80) \times 10^{-11}\,\mathrm{m}\)
\(m_{\mathrm{e}}\) Electron mass \(9.109\,383\,7015(28) \times 10^{-31}\,\mathrm{kg}\)
\(m_{\mathrm{p}}\) Proton mass \(1.672\,621\,923\,69(51) \times 10^{-27}\,\mathrm{kg}\)