Physical Constants and Conversions

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

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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

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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

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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

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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

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Radioactivity

• 1 Curie 3.7e10 counts/s

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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

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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