Here, we will provide you with a self-consistent set of internationally recommended values of the basic constants and conversion factors of physics based on all of the relevant data available at a given point in time. There will be an adjustment of the constants based on the revised of the International System of Units (SI).
Physical Constants
| Constant Name | Symbol | Value | Unit | Useful Combinations |
|---|---|---|---|---|
| Speed of light | $c$ | $$3.00 \times 10^8$$ | $$\frac{m}{s}$$ | |
| Gravitational constant | $G$ | $6.67 \times 10^{−11} $ | $\frac{Nm^2}{kg^2}$ | |
| Avogadro’s number | $N_A$ | $6.02 \times 10^{23}$ | $\frac{practical}{mol}$ | |
| Elementary charge | $e$ | $1.6 \times 10^{-19}$ | $C$ | $1 \;\mathrm{eV} = 1.6 \times 10^{-19} \;\mathrm{Joule}$ |
| Permittivity of free space | $\varepsilon_0$ | $8.85 \times 10^{-12}$ | $\frac{C^2}{N \cdot m^2}$ | |
| Planck’s constant | $h$ | $6.63 \times 10^{-34}$ | $J.s$ |
Planck's constant times speed of light: $hc=1240 \;\mathrm{eV \cdot nm}$ Reduced Planck’s constant: $\hbar = \dfrac{h}{2 \pi} = 1.05 \times 10^{-34} \;\mathrm{J \cdot s}$ Reduced planck's constant times speed of light: $\hbar c=197 \;\mathrm{eV \cdot nm}$ |
| Coulomb force constant | $k_e$ | $8.99 \times 10^9$ | $\frac{N.m^2}{C}$ |
Electric force constant: $k_e = \dfrac{1}{4 \pi \varepsilon_0}$ $k_e$ times elementry charge square: $\dfrac{e^2}{4 \pi \varepsilon_0}=1.44 \;\mathrm{eV \cdot nm}$ |
| Fine structure constant | $\alpha$ | $0.0730 \approx \dfrac{1}{137}$ | Fine structure constant: $\alpha = \dfrac{k_e e^2}{\hbar c}$ | |
| Permeability of vacuum | $\mu_0$ | $1.2566 \times 10^{8}$ | $\frac{N}{A^2}$ |
Magnetic constant: $\mu_0 = 4 \pi \times 10^{-7}\;\mathrm{ \dfrac{T.m}{A}}$ $1 \;\mathrm{T} = 10^{4} \;\mathrm{G}$ |
| Boltzman’s constant | $k_B$ | $1.38 \times 10^{-23}$ | $\frac{J}{K}$ | Boltzman’s constant: $k=8.617\times 10^{-5} \;\mathrm{eV/K}$ |
| Gas constant | $R$ | $8.31$ | $\frac{J}{mol.K}$ | Gas constant: $R=N_A k_B$ |
Masses and Distances
| Constant Name | Symbol | Value | Unit | Useful Combinations |
|---|---|---|---|---|
| Unified mass unit | $u$ | $$1.66 \times 10^{-27}$$ | $kg$ |
Unified mass unit: $u = 931.5 \;\mathrm{MeV / c^2}$ $$1 \;\mathrm{u} \approx m_{proton} \approx m_{neutron} \approx m_{hydrogen.atom}$$ |
| Mass of proton | $m_p$ | $1.67 \times 10^{-27}$ | $kg$ | Mass of proton: $m_p = 938 \;\mathrm{MeV / c^2}$ |
| Mass of electron | $m_e$ | $9.11 \times 10^{-31}$ | $kg$ | Mass of electron: $m_e = 0.511 \;\mathrm{MeV / c^2}$ |
| Mass of alpha particle | $m_{\alpha}$ | $6.64 \times 10^{-27}$ | $kg$ | Mass of alpha particle: $m_{\alpha} = 3727 \;\mathrm{MeV / c^2}$ |
Miscellaneous
| Constant Name | Symbol | Value | Unit | Useful Combinations |
|---|---|---|---|---|
| Gravitational acceleration | $g$ | $9.8$ |
$\frac{m}{s^2}$ $\frac{N}{kg}$ |
magnitude near the Earth's surface |
You don`t have permission to comment here!
Report