# Commonly Used Physical Constants

Uncertainty should be read as 1.234(56) = 1.234$\pm$0.056 :
| Name | Symbol | Value | Units | Relative Uncertainty |
| Speed of light (in vacuum) | $c$ | $299\ 792\ 458$ | $\mathrm {m} \ \mathrm {s} ^{-1}$ | (exact) |
| Magnetic Constant | $\mu _{0}$ | $4\pi \times 10^{-7}\approx 12.566\ 370\ 6\times 10^{-7}$ | $\mathrm {N} \ \mathrm {A} ^{-2}$ | (exact) |
| Electric Constant | $\varepsilon _{0}=1/\left(\mu _{0}c^{2}\right)$ | $\approx 8.854\ 187\ 817\times 10^{-12}$ | $\mathrm {F} \ \mathrm {m} ^{-1}$ | (exact) |
| Newtonian Gravitaional Constant | $G$ | $6.674\ 2(10)\times 10^{-11}$ | $\mathrm {m} ^{3}\ \mathrm {kg} ^{-1}\ \mathrm {s} ^{-2}$ | $1.5\times 10^{-4}$ |
| Plank's Constant | $h$ | $6.626\ 069\ 3(11)\times 10^{-34}$ | $\mathrm {J} \ \mathrm {s}$ | $1.7\times 10^{-7}$ |
| Elementary charge | $e$ | $1.602\ 176\ 53(14)\times 10^{-19}$ | $\mathrm {C}$ | $8.5\times 10^{-8}$ |
| Mass of the electron | $m_{e}$ | $9.109\ 382\ 6(16)\times 10^{-31}$ | $\mathrm {kg}$ | $1.7\times 10^{-7}$ |
| Mass of the proton | $m_{p}$ | $1.672\ 621\ 71(29)\times 10^{-27}$ | $\mathrm {kg}$ | $1.7\times 10^{-7}$ |
| Fine structure constant | $\alpha ={\frac {e^{2}}{4\pi \varepsilon _{0}\hbar c}}$ | $7.297\ 352\ 568(24)\times 10^{-3}$ | dimensionless | $3.3\times 10^{-9}$ |
| Molar gass constant | $R$ | $8.314\ 472(15)$ | $\mathrm {J} \ \mathrm {mol} ^{-1}\ \mathrm {K} ^{-1}$ | $1.7\times 10^{-6}$ |
| Boltzmann's constant | $k$ | $1.380\ 650\ 5(24)\times 10^{-23}$ | $\mathrm {J} \ \mathrm {K} ^{-1}$ | $1.8\times 10^{-6}$ |
| Avogadro's Number | $N_{\text{A}},L$ | $6.022\ 141\ 5(10)\times 10^{23}$ | $\mathrm {mol} ^{-1}$ | $1.7\times 10^{-7}$ |
| Rydberg constant | $R_{\infty }$ | $10\ 973\ 731.568\ 525(73)$ | $\mathrm {m} ^{-1}$ | $6.6\times 10^{-12}$ |
| Standard acceleration of gravity | $g$ | $9.806\ 65$ | $\mathrm {m} \ \mathrm {s} ^{-2}$ | defined |
| Atmospheric pressure | $\mathrm {atm}$ | $101\ 325$ | $\mathrm {Pa}$ | defined |
| Bohr Radius | $a_{0}\$ | $0.529\ 177\ 208\ 59(36)\times 10^{-10}\$ | $\mathrm {m} \$ | $6.8\times 10^{-10}$ |
| Electron Volt | $eV$ | $1.602\ 176\ 53(14)\times 10^{-19}$ | $\mathrm {J}$ | $8.7\times 10^{-8}$ |
| Luminous efficacy of monochromatic radiation | $K_{cd}$ | $683$ | $\mathrm {lm/W}$ | (exact) |
| hyperfine transition frequency of Cs-133 | $\Delta \nu _{\text{Cs}}$ | $9\ 192\ 631\ 770$ | $\mathrm {Hz}$ | (exact) |
| Reduced Planck constant | $\hbar =h/2\pi$ | $1.054\ 571\ 817\times {10}^{-34}$ | $\mathrm {J} \cdot \mathrm {s}$ | (exact) |
| atomic mass of Carbon 12 | $m(^{12}{\text{C}})$ | $1.992\ 646\ 879\ 92(60)\times {10}^{-26}$ | $\mathrm {kg}$ | |
| molar mass of Carbon-12 | $M(^{12}{\text{C}})=N_{\text{A}}m(^{12}{\text{C}})$ | $11.999\ 999\ 9958(36)\times {10}^{-3}$ | $\mathrm {kg\cdot {mol}^{-1}}$ | |
| atomic mass constant | $m_{\text{u}}=m(^{12}{\text{C}})/12=1\,{\text{Da}}$ | $1.660\ 539\ 066\ 60(50)\times {10}^{-27}$ | $\mathrm {kg}$ | |
| molar mass constant | $M_{\text{u}}=M(^{12}{\text{C}})/12=N_{\text{A}}m_{\text{u}}$ | $0.999\ 999\ 999\ 65(30)\times {10}^{-3}$ | $\mathrm {kg\cdot {mol}^{-1}}$ | |
| molar volume of silicon | $V_{m}(\mathrm {Si} )$ | $1.205\ 883\ 199(60)\times {10}^{-5}$ | $\mathrm {m^{3}\cdot {mol}^{-1}}$ | |
| molar Planck constant | $N_{\text{A}}h$ | $3.990\ 312\ 712\ldots {10}^{-10}$ | $\mathrm {J\cdot {Hz}^{-1}\cdot {mol}^{-1}}$ | |
| Stefan-Boltzmann constant | $\sigma =\pi ^{2}k_{B}^{4}/60\hbar ^{3}c^{2}$ | $5.670\ 374\ 419\ldots \times {10}^{-8}$ | $\mathrm {W\cdot m^{-2}\cdot K^{-4}}$ | |
| first radiation constant | $c_{1}=2\pi hc^{2}$ | $3.741\ 771\ 852\ldots {10}^{-16}$ | $\mathrm {W\cdot m^{2}}$ | |
| first radiation constant for spectral radiance | $c_{\text{1L}}=2hc^{2}/sr$ | $1.191\ 042\ 972\ 397\ 188\ 414\ 079\ 4892\times {10}^{-16}$ | $\mathrm {W\cdot m^{2}{sr}^{-1}}$ | |
| second radiation constant | $c_{2}=hc/k_{B}$ | $1.438\ 776\ 877\ldots \times {10}^{-2}$ | $\mathrm {m\cdot K}$ | |
| Wien wavelength displacement constant | $b$ | $2.897\ 771\ 955\ldots \times {10}^{-3}$ | $\mathrm {m\cdot K}$ | |
| Wien frequency displacement constant | $b'=c/b$ | $5.878\ 925\ 757\ \times {10}^{10}$ | $\mathrm {Hz\cdot K^{-1}}$ | |
| Wien entropy displacement constant | $b_{\text{entropy}}$ | $3.002\ 916\ 077\ldots \times {10}^{-3}$ | $\mathrm {m\cdot K}$ | |
| Faraday constant | $F=N_{\text{A}}e$ | $96\ 485.332\ 123\ 310\ 0184$ | $\mathrm {C\cdot {mol}^{-1}}$ | |

## To Be Merged Into Table

This list is prepared in the format
* Constant (symbol) : value
* Coulomb's Law Constant (k) : 1/(4 π ε$_0$) = 9.0 × 10$^9$ N·m$^2$/C$^2$
* Faraday constant (F) : 96,485 C·mol$^{−1}$
* Mass of a neutron (m$_n$) : 1.67495 × 10$^{−27}$ kg
* Mass of Earth : 5.98 × 10$^{24}$ kg
* Mass of the Moon : 7.35 × 10$^{22}$ kg
* Mean radius of Earth : 6.37 × 10$^6$ m
* Mean radius of the Moon : 1.74 × 10$^6$ m
* Dirac's Constant ($\hbar$) : $h/(2\pi )$ = 1.05457148 × 10$^{−34}$ J·s
* Speed of sound in air at STP : 3.31 × 10$^2$ m/s
* Unified Atomic Mass Unit (u) : 1.66 × 10$^{−27}$ kg
| Item | Proton | Neutron | Electron |
| Mass | 1 | 1 | Negligible |
| Charge | +1 | 0 | -1 |

# See Also
## Wiki-links

* Wikipedia Article

## External Links

* NIST Physics Lab
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* ↑ "first radiation constant for spectral radiance". NIST.gov. NIST. Retrieved 5 June 2022.
* ↑ "Faraday constant". NIST.gov. NIST. Retrieved 5 June 2022.