Physics Constants
Shared 5/19/2026•3 views
### Fundamental Constants - **Speed of Light ($c$):** $299,792,458 \text{ m/s}$ (exact) - **Planck's Constant ($h$):** $6.62607015 \times 10^{-34} \text{ J}\cdot\text{s}$ (exact) - **Reduced Planck's Constant ($\hbar$):** $h / (2\pi) = 1.054571817 \times 10^{-34} \text{ J}\cdot\text{s}$ (exact) - **Elementary Charge ($e$):** $1.602176634 \times 10^{-19} \text{ C}$ (exact) - **Boltzmann Constant ($k_B$):** $1.380649 \times 10^{-23} \text{ J/K}$ (exact) - **Avogadro Constant ($N_A$):** $6.02214076 \times 10^{23} \text{ mol}^{-1}$ (exact) - **Gas Constant ($R$):** $N_A k_B = 8.314462618 \text{ J/(mol}\cdot\text{K)}$ (exact) - **Gravitational Constant ($G$):** $6.67430(15) \times 10^{-11} \text{ N}\cdot\text{m}^2/\text{kg}^2$ - **Vacuum Permittivity ($\epsilon_0$):** $1 / (\mu_0 c^2) = 8.8541878128(13) \times 10^{-12} \text{ F/m}$ - **Vacuum Permeability ($\mu_0$):** $4\pi \times 10^{-7} \text{ N/A}^2$ (exact) - **Fine-structure Constant ($\alpha$):** $e^2 / (4\pi\epsilon_0 \hbar c) \approx 1/137.035999084$ ### Electromagnetism Constants - **Coulomb's Constant ($k_e$ or $k$):** $1 / (4\pi\epsilon_0) = 8.9875517923 \times 10^9 \text{ N}\cdot\text{m}^2/\text{C}^2$ - **Magnetic Flux Quantum ($\Phi_0$):** $h / (2e) = 2.067833848 \times 10^{-15} \text{ Wb}$ ### Atomic and Nuclear Constants - **Electron Mass ($m_e$):** $9.1093837015(28) \times 10^{-31} \text{ kg}$ - **Proton Mass ($m_p$):** $1.67262192369(51) \times 10^{-27} \text{ kg}$ - **Neutron Mass ($m_n$):** $1.67492749804(95) \times 10^{-27} \text{ kg}$ - **Atomic Mass Unit (amu or u):** $1.66053906660(50) \times 10^{-27} \text{ kg}$ - **Rydberg Constant ($R_\infty$):** $10973731.568160(21) \text{ m}^{-1}$ - **Bohr Radius ($a_0$):** $0.529177210903(15) \times 10^{-10} \text{ m}$ - **Bohr Magneton ($\mu_B$):** $9.2740100160(23) \times 10^{-24} \text{ J/T}$ - **Nuclear Magneton ($\mu_N$):** $5.0507837461(15) \times 10^{-27} \text{ J/T}$ - **Electron Rest Energy ($m_e c^2$):** $0.51099895000(15) \text{ MeV}$ - **Proton Rest Energy ($m_p c^2$):** $938.27208816(29) \text{ MeV}$ - **Neutron Rest Energy ($m_n c^2$):** $939.56542052(54) \text{ MeV}$ ### Thermodynamics Constants - **Stefan-Boltzmann Constant ($\sigma$):** $5.670374419 \times 10^{-8} \text{ W/(m}^2\cdot\text{K}^4)$ - **Wien's Displacement Law Constant ($b$):** $2.898 \times 10^{-3} \text{ m}\cdot\text{K}$ ### Astronomical Constants (Approximate) - **Solar Mass ($M_\odot$):** $1.989 \times 10^{30} \text{ kg}$ - **Earth Mass ($M_\oplus$):** $5.972 \times 10^{24} \text{ kg}$ - **Astronomical Unit (AU):** $1.495978707 \times 10^{11} \text{ m}$ (exact) - **Parsec (pc):** $3.08567758149 \times 10^{16} \text{ m}$ - **Light Year (ly):** $9.4607 \times 10^{15} \text{ m}$ ### Common Conversion Factors - **Electron Volt (eV):** $1.602176634 \times 10^{-19} \text{ J}$ - **Standard Gravity ($g$):** $9.80665 \text{ m/s}^2$ (exact) - **Atmosphere (atm):** $101325 \text{ Pa}$ (exact) - **Celsius to Kelvin ($T_K$):** $T_K = T_C + 273.15$
