# Commonly Used Physical Constants

Uncertainty should be read as 1.234(56) = 1.234${\displaystyle \pm }$0.056
Name Symbol Value Units Relative Uncertainty
Speed of light (in vacuum) ${\displaystyle c}$ ${\displaystyle 299\ 792\ 458}$ ${\displaystyle \mathrm {m} \ \mathrm {s} ^{-1}}$ (exact)
Magnetic Constant ${\displaystyle \mu _{0}}$ ${\displaystyle 4\pi \times 10^{-7}\approx 12.566\ 370\ 6\times 10^{-7}}$ ${\displaystyle \mathrm {N} \ \mathrm {A} ^{-2}}$ (exact)
Electric Constant ${\displaystyle \varepsilon _{0}=1/\left(\mu _{0}c^{2}\right)}$ ${\displaystyle \approx 8.854\ 187\ 817\times 10^{-12}}$ ${\displaystyle \mathrm {F} \ \mathrm {m} ^{-1}}$ (exact)
Newtonian Gravitaional Constant ${\displaystyle G}$ ${\displaystyle 6.674\ 2(10)\times 10^{-11}}$ ${\displaystyle \mathrm {m} ^{3}\ \mathrm {kg} ^{-1}\ \mathrm {s} ^{-2}}$ ${\displaystyle 1.5\times 10^{-4}}$
Plank's Constant ${\displaystyle h}$ ${\displaystyle 6.626\ 069\ 3(11)\times 10^{-34}}$ ${\displaystyle \mathrm {J} \ \mathrm {s} }$ ${\displaystyle 1.7\times 10^{-7}}$
Elementary charge ${\displaystyle e}$ ${\displaystyle 1.602\ 176\ 53(14)\times 10^{-19}}$ ${\displaystyle \mathrm {C} }$ ${\displaystyle 8.5\times 10^{-8}}$
Mass of the electron ${\displaystyle m_{e}}$ ${\displaystyle 9.109\ 382\ 6(16)\times 10^{-31}}$ ${\displaystyle \mathrm {kg} }$ ${\displaystyle 1.7\times 10^{-7}}$
Mass of the proton ${\displaystyle m_{p}}$ ${\displaystyle 1.672\ 621\ 71(29)\times 10^{-27}}$ ${\displaystyle \mathrm {kg} }$ ${\displaystyle 1.7\times 10^{-7}}$
Fine structure constant ${\displaystyle \alpha ={\frac {e^{2}}{4\pi \varepsilon _{0}\hbar c}}}$ ${\displaystyle 7.297\ 352\ 568(24)\times 10^{-3}}$ dimensionless ${\displaystyle 3.3\times 10^{-9}}$
Molar gass constant ${\displaystyle R}$ ${\displaystyle 8.314\ 472(15)}$ ${\displaystyle \mathrm {J} \ \mathrm {mol} ^{-1}\ \mathrm {K} ^{-1}}$ ${\displaystyle 1.7\times 10^{-6}}$
Boltzman's constant ${\displaystyle k}$ ${\displaystyle 1.380\ 650\ 5(24)\times 10^{-23}}$ ${\displaystyle \mathrm {J} \ \mathrm {K} ^{-1}}$ ${\displaystyle 1.8\times 10^{-6}}$
Avogadro's Number ${\displaystyle N_{A}}$ ${\displaystyle 6.022\ 141\ 5(10)\times 10^{23}}$ ${\displaystyle \mathrm {mol} ^{-1}}$ ${\displaystyle 1.7\times 10^{-7}}$
Rydberg constant ${\displaystyle R_{\infty }}$ ${\displaystyle 10\ 973\ 731.568\ 525(73)}$ ${\displaystyle \mathrm {m} ^{-1}}$ ${\displaystyle 6.6\times 10^{-12}}$
Standard acceleration of gravity ${\displaystyle g}$ ${\displaystyle 9.806\ 65}$ ${\displaystyle \mathrm {m} \ \mathrm {s} ^{-2}}$ defined
Atmospheric pressure ${\displaystyle \mathrm {atm} }$ ${\displaystyle 101\ 325}$ ${\displaystyle \mathrm {Pa} }$ defined
Bohr Radius ${\displaystyle a_{0}\ }$ ${\displaystyle 0.529\ 177\ 208\ 59(36)\times 10^{-10}\ }$ ${\displaystyle \mathrm {m} \ }$ ${\displaystyle 6.8\times 10^{-10}}$
Electron Volt ${\displaystyle eV}$ ${\displaystyle 1.602\ 176\ 53(14)\times 10^{-19}}$ ${\displaystyle \mathrm {J} }$ ${\displaystyle 8.7\times 10^{-8}}$

## To Be Merged Into Table

This list is prepared in the format

• Constant (symbol) : value

• Coulomb's Law Constant (k) : 1/(4 π ε0) = 9.0 × 109 N·m2/C2
• Faraday constant (F)  : 96,485 C·mol−1
• Mass of a neutron (mn) : 1.67495 × 10−27 kg
• Mass of Earth : 5.98 × 1024 kg
• Mass of the Moon : 7.35 × 1022 kg
• Mean radius of Earth : 6.37 × 106 m
• Mean radius of the Moon : 1.74 × 106 m
• Dirac's Constant (${\displaystyle \hbar }$) : ${\displaystyle h/(2\pi )}$ = 1.05457148 × 10−34 J·s
• Speed of sound in air at STP : 3.31 × 102 m/s
• Unified Atomic Mass Unit (u) : 1.66 × 10−27 kg
 Item Proton Neutron Electron Mass 1 1 Negligible Charge +1 0 -1