The National Institute of Standards and Technology (NIST)
The National Institute of Standards and Technology (NIST) in Washington, DC, provides highly accurate values for fundamental physical constants. These constants are essential in the fields of physics, chemistry, and engineering. Below are some of the key constants provided by NIST.
Avogadro's Number (NA)
NA = 6.022 × 1023 mol–1 ≈ 6.022 × 1023 atoms/mol
NA = 6.022 × 1023 mol–1 ≈ 6.022 × 1023 atoms/mol
Speed of Light (c)
c = 2.998 × 108 m/s ≈ 3 × 108 m/s
c = 2.998 × 108 m/s ≈ 3 × 108 m/s
Electron Charge (e)
e = 1.602 × 10–19 C
e = 1.602 × 10–19 C
Electron Rest Mass (me)
me = 0.511 MeV/c2
me = 0.511 MeV/c2
Proton Rest Mass (mp)
mp = 938.3 MeV/c2
mp = 938.3 MeV/c2
Neutron Rest Mass (mn)
mn = 939.6 MeV/c2
mn = 939.6 MeV/c2
Atomic Mass Unit (u)
u = 931.5 MeV/c2
u = 931.5 MeV/c2
Planck's Constant (h)
h = 6.626 × 10–34 J·s
h = 6.626 × 10–34 J·s
Electric Constant (ε0)
ε0 = 8.854 × 10–12 C·V–1·m–1
ε0 = 8.854 × 10–12 C·V–1·m–1
Magnetic Constant (μ0)
μ0 = 4π × 10–7 V·s·A–1·m–1
μ0 = 4π × 10–7 V·s·A–1·m–1
Gravitational Constant (G)
G = 6.672 × 10–11 m3·kg–1·s–2
G = 6.672 × 10–11 m3·kg–1·s–2
Proton Mass / Electron Mass (mp / me)
mp / me = 1836.0
mp / me = 1836.0
Specific Charge of Electron (e / me)
e / me = 1.758 × 1011 C/kg
e / me = 1.758 × 1011 C/kg
For more detailed information on these constants and other scientific data, visit the National Institute of Standards and Technology.