constants

Constants (scipy.constants)

Physical and mathematical constants and units.

Mathematical constants

pi Pi
golden Golden ratio
golden_ratio Golden ratio

Physical constants

c speed of light in vacuum
speed_of_light speed of light in vacuum
mu_0 the magnetic constant
epsilon_0 the electric constant (vacuum permittivity),
h the Planck constant
Planck the Planck constant
hbar
G Newtonian constant of gravitation
gravitational_constant Newtonian constant of gravitation
g standard acceleration of gravity
e elementary charge
elementary_charge elementary charge
R molar gas constant
gas_constant molar gas constant
alpha fine-structure constant
fine_structure fine-structure constant
N_A Avogadro constant
Avogadro Avogadro constant
k Boltzmann constant
Boltzmann Boltzmann constant
sigma Stefan-Boltzmann constant
Stefan_Boltzmann Stefan-Boltzmann constant
Wien Wien displacement law constant
Rydberg Rydberg constant
m_e electron mass
electron_mass electron mass
m_p proton mass
proton_mass proton mass
m_n neutron mass
neutron_mass neutron mass

Constants database

In addition to the above variables, scipy.constants also contains the 2014 CODATA recommended values [CODATA2014] database containing more physical constants.

value
unit
precision
find
ConstantWarning
physical_constants

Dictionary of physical constants, of the format physical_constants[name] = (value, unit, uncertainty).

Available constants:

%(constant_names)s  

Units

SI prefixes

yotta
zetta
exa
peta
tera
giga
mega
kilo
hecto
deka
deci
centi
milli
micro
nano
pico
femto
atto
zepto

Binary prefixes

kibi
mebi
gibi
tebi
pebi
exbi
zebi
yobi

Mass

gram kg
metric_ton kg
grain one grain in kg
lb one pound (avoirdupous) in kg
pound one pound (avoirdupous) in kg
blob one inch version of a slug in kg (added in 1.0.0)
slinch one inch version of a slug in kg (added in 1.0.0)
slug one slug in kg (added in 1.0.0)
oz one ounce in kg
ounce one ounce in kg
stone one stone in kg
grain one grain in kg
long_ton one long ton in kg
short_ton one short ton in kg
troy_ounce one Troy ounce in kg
troy_pound one Troy pound in kg
carat one carat in kg
m_u atomic mass constant (in kg)
u atomic mass constant (in kg)
atomic_mass atomic mass constant (in kg)

Angle

degree degree in radians
arcmin arc minute in radians
arcminute arc minute in radians
arcsec arc second in radians
arcsecond arc second in radians

Time

minute one minute in seconds
hour one hour in seconds
day one day in seconds
week one week in seconds
year one year (365 days) in seconds
Julian_year one Julian year (365.25 days) in seconds

Length

inch one inch in meters
foot one foot in meters
yard one yard in meters
mile one mile in meters
mil one mil in meters
pt one point in meters
point one point in meters
survey_foot one survey foot in meters
survey_mile one survey mile in meters
nautical_mile one nautical mile in meters
fermi one Fermi in meters
angstrom one Angstrom in meters
micron one micron in meters
au one astronomical unit in meters
astronomical_unit one astronomical unit in meters
light_year one light year in meters
parsec one parsec in meters

Pressure

atm standard atmosphere in pascals
atmosphere standard atmosphere in pascals
bar one bar in pascals
torr one torr (mmHg) in pascals
mmHg one torr (mmHg) in pascals
psi one psi in pascals

Area

hectare one hectare in square meters
acre one acre in square meters

Volume

liter one liter in cubic meters
litre one liter in cubic meters
gallon one gallon (US) in cubic meters
gallon_US one gallon (US) in cubic meters
gallon_imp one gallon (UK) in cubic meters
fluid_ounce one fluid ounce (US) in cubic meters
fluid_ounce_US one fluid ounce (US) in cubic meters
fluid_ounce_imp one fluid ounce (UK) in cubic meters
bbl one barrel in cubic meters
barrel one barrel in cubic meters

Speed

kmh kilometers per hour in meters per second
mph miles per hour in meters per second
mach one Mach (approx., at 15 C, 1 atm) in meters per second
speed_of_sound one Mach (approx., at 15 C, 1 atm) in meters per second
knot one knot in meters per second

Temperature

zero_Celsius zero of Celsius scale in Kelvin
degree_Fahrenheit one Fahrenheit (only differences) in Kelvins
convert_temperature

Energy

eV one electron volt in Joules
electron_volt one electron volt in Joules
calorie one calorie (thermochemical) in Joules
calorie_th one calorie (thermochemical) in Joules
calorie_IT one calorie (International Steam Table calorie, 1956) in Joules
erg one erg in Joules
Btu one British thermal unit (International Steam Table) in Joules
Btu_IT one British thermal unit (International Steam Table) in Joules
Btu_th one British thermal unit (thermochemical) in Joules
ton_TNT one ton of TNT in Joules

Power

hp one horsepower in watts
horsepower one horsepower in watts

Force

dyn one dyne in newtons
dyne one dyne in newtons
lbf one pound force in newtons
pound_force one pound force in newtons
kgf one kilogram force in newtons
kilogram_force one kilogram force in newtons

Optics

lambda2nu
nu2lambda

References

[CODATA2014]

CODATA Recommended Values of the Fundamental Physical Constants 2014.

http://physics.nist.gov/cuu/Constants/index.html

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