Physical Constants | Conversion Factors

Physical Constants and Conversions

Basic | Electrical | Nuclear | Chemistry/Thermo | Pressures | Radioactivity | Astronomical Units | Optical Constants

Basic

Speed of light in vacuum c = 2.997 924 580 e8 m/s (exact)

Planck's constant

h = 6.6260755e-34 J-s

h = 4.136e-15 eV-s

hbar = h/2\pi = 1.05457266e-34 J-s

hbar = 6.57e-16 eV-s

electron charge q = 1.60217733e-19 coulomb

Gravitational Constant G 6.7259e-11 N m**2/kg**2

Boltzmann's constant

k = 1.380658e-23 J/K

k = 8.617e-5 eV/K

Stephan-Boltzmann constant \sigma = 5.67051e-8 W/m**2/K**4

Electrical

Permittivity of free space

\epsilon = 8.854e-12 F/m = 1/c**2\mu

\epsilon = 55.3 e/V-micron

Permeability of free space \mu = 4 \pi e-7 H/m or Tesla/ampere

Coulomb constant 8.988e9 N-m**2/coul**2

Wavelength of a 1eV photon 1.243e-6 m

thermal electron voltage (r.t.) kT/q = 25.86 mv

energy of electron (r.t.) kT = .02586 eV

energy (1 electron volt) 1 ev = 1.602e-19 J

Quantum Hall Resistance 25812.8056 ohms

Nuclear

Electron Rest Mass 9.1093897e-28 g

Proton Rest Mass 1.6726231e-24 g

Neutron Rest Mass 1.6749286e-24 g

Magnetic flux quantum (hc/2e) 2.06783461e-15 Wb

Quantum of circulation (h/2m_e) 3.63694807e-4 m**2/s

Specific Electron Charge -e/m_e - 1.75881962e11 Coul/kg

Electron Magnetic Moment \mu_e 9.2847701e-24 J/T

Bohr Magneton 9.2740154e-24 J/Tesla

Nuclear Magneton e h-bar/2m_p 5.0507866e-27 J/T

Proton Magnetic Moment \mu_p 1.41060761e-26 J/T

Chemistry/Thermo

Faraday Constant F 9.6485309e4 Coulombs/mole

Gas Constant R 8.314510 J/K/mole

energy (calories) 1 cal = 4.184 J

Bohr radius .529 angstrom

Avogadro's number 6.0221367e23 atoms/mole

Molar volume

at 273.15K 1e5 Pa 22.71108e-3 m**3/mole

at 273.15K 1 atm 22.41410e-3 m**3/mole

atomic mass unit 1.6605402e-24 g

Pressures

Standard pressure (1 atm) 1.01325e5 Pa (Newton/m**2)

1 Torr = 1 mm Hg = 133.3 N/m**2 = 133.3 Pa

1 psi = 6.89e3 Pa

Radioactivity

1 Curie 3.7e10 counts/s

Astronomical Units

Solar Mass 1.989e33 g

Solar Radius 6.9599e10 cm

Solar luminosity 3.826e33 ergs/s

Gravity at solar surface 2.74e4 cm/s**2

Earth mass 5.976e27 g

Earth equatorial radius 6378.164 km

Gravity at earth's surface 980.665 cm/s**2

Astronomical Unit 1.4959780e13 cm

Solar effective temperature 5800K

Solar magnitude -26.73

Solar constant (1976) .1353 W/cm**2

Julian century 36525 ephemeris days

Tropical year (1900.0) 365.242 days

Tropical year (1900.0) 3.1557e7 ephemeris seconds

Ephemeris Day 86400 ephemeris seconds

solar motion velocity 19.7 km/s

Julian date for 1 Jan 1981: 2444605.5 days

parsec 3.261633 light years

parsec 3.085678e18 cm

light year 9.460530e17 cm

Xu 1.00208e-11 cm

flux unit = Jansky = 1e-26 W/m**2/Hz

Hubble constant 72 km/s/Mpc

Optical Constants

1 candle = 1 lumen/steradian

1 candle/m**2 = 3.142e-4 lambert

1 lambert = 2.054 candles/in**2

1 lux = 1 meter-candle

1 lux = .0929 foot-candle

1 lumen = 1 candle into an angle of 1 steradian

1 lumen = .001495 watts of light at 546 nm