Constants
const get <name>
Description
Get the value of a physical constant (SI unit).
Names (case sensitive):
- universal: c, h, hbar, G, mu0, eps0, Z0, k
- electromagnetic: e, Phi0, G0, KJ, RK, muB, muN
- atomic: me, mp, mn, mmu, u, alpha, Rinf, a0, re, lambdaC, Eh, ge, mue, mup, mec2 (MeV), mpc2 (MeV)
- physicochemical: NA, R, F, sigma, b, c1, c2, Vm, n0, eV
- adopted: g0, atm, dnuCs, Kcd
Get the value of a physical constant (SI unit).
Names (case sensitive):
- universal: c, h, hbar, G, mu0, eps0, Z0, k
- electromagnetic: e, Phi0, G0, KJ, RK, muB, muN
- atomic: me, mp, mn, mmu, u, alpha, Rinf, a0, re, lambdaC, Eh, ge, mue, mup, mec2 (MeV), mpc2 (MeV)
- physicochemical: NA, R, F, sigma, b, c1, c2, Vm, n0, eV
- adopted: g0, atm, dnuCs, Kcd
Parameters
name: The name of the constant - String - required
name: The name of the constant - String - required
admin
const get "G"
mentdb
6.6743E-11
admin
const get "NA"
mentdb
6.02214076E23
Planck constant
admin
const get "h"
mentdb
6.62607015E-34
Electron mass
admin
const get "me"
mentdb
9.1093837139E-31
Standard gravity (g0)
admin
const get "g0"
mentdb
9.80665
Boltzmann constant
admin
const get "k"
mentdb
1.380649E-23
Elementary charge
admin
const get "e"
mentdb
1.602176634E-19
Gas constant
admin
const get "R"
mentdb
8.31446261815324
Use in an expression: k T at 300 K in eV
admin
unit calc "_k * 300 K" "eV"
mentdb
0.0258519997864355
Unknown constant: error
admin
const get "foo"
mentdb
Sorry, an error appears (unknown constant 'foo' (see 'const list')).
const info <name>
Description
Get a physical constant as a JSON object: name, description, value, standard uncertainty, exact, unit, category
Get a physical constant as a JSON object: name, description, value, standard uncertainty, exact, unit, category
Parameters
name: The name of the constant - String - required
name: The name of the constant - String - required
admin
const info "G"
mentdb
{"name": "G", "description": "Newtonian constant of gravitation", "value": 6.6743E-11, "uncertainty": 1.5E-15, "exact": false, "unit": "m^3 kg^-1 s^-2", "category": "universal"}
Speed of light
admin
const info "c"
mentdb
{"name": "c", "description": "speed of light in vacuum", "value": 2.99792458E8, "uncertainty": 0, "exact": true, "unit": "m s^-1", "category": "universal"}
Electron mass
admin
const info "me"
mentdb
{"name": "me", "description": "electron mass", "value": 9.1093837139E-31, "uncertainty": 2.8E-40, "exact": false, "unit": "kg", "category": "atomic"}
Fine-structure constant
admin
const info "alpha"
mentdb
{"name": "alpha", "description": "fine-structure constant", "value": 0.0072973525643, "uncertainty": 1.1E-12, "exact": false, "unit": "", "category": "atomic"}
const list
Description
List all the physical constants (JSON array of objects, same fields as 'const info')
List all the physical constants (JSON array of objects, same fields as 'const info')
admin
const list
mentdb
[ {"name": "c", "description": "speed of light in vacuum", "value": 2.99792458E8, "uncertainty": 0, "exact": true, "unit": "m s^-1", "category": "universal"}, ... ]
const list <category>
Description
List the physical constants of a category: universal, electromagnetic, atomic, physicochemical, adopted
List the physical constants of a category: universal, electromagnetic, atomic, physicochemical, adopted
Parameters
category: The category - String - required
category: The category - String - required
admin
const list "adopted"
mentdb
[ {"name": "g0", "description": "standard acceleration of gravity", "value": 9.80665, "uncertainty": 0, "exact": true, "unit": "m s^-2", "category": "adopted"}, ... ]
Atomic constants
admin
const list "atomic"
mentdb
[ {"name": "me", "description": "electron mass", "value": 9.1093837139E-31, "uncertainty": 2.8E-40, "exact": false, "unit": "kg", "category": "atomic"}, {"name": "mp", "description": "proton mass", "value": 1.67262192595E-27, "uncertainty": 5.2E-37, "exact": false, "unit": "kg", "category": "atomic"}, {"name": "mn", "description": "neutron mass", "value": 1.67492750056E-27, "uncertainty": 8.5E-37, "exact": false, "unit": "kg", "category": "atomic"}, {"name": "mmu", "description": "muon mass", "value": 1.883531627E-28, "uncertainty": 4.2E-36, "exact": false, "unit": "kg", "category": "atomic"}, {"name": "u", "description": "atomic mass constant (dalton)", "value": 1.66053906892E-27, "uncertainty": 5.2E-37, "exact": false, "unit": "kg", "category": "atomic"}, {"name": "alpha", "description": "fine-structure constant", "value": 0.0072973525643, "uncertainty": 1.1E-12, "exact": false, "unit": "", "category": "atomic"}, {"name": "Rinf", "description": "Rydberg constant", "value": 1.0973731568157E7, "uncertainty": 1.2E-5, "exact": false, "unit": "m^-1", "category": "atomic"}, {"name": "a0", "description": "Bohr radius", "value": 5.29177210544E-11, "uncertainty": 8.2E-21, "exact": false, "unit": "m", "category": "atomic"}, {"name": "re", "description": "classical electron radius", "value": 2.8179403205E-15, "uncertainty": 1.3E-24, "exact": false, "unit": "m", "category": "atomic"}, {"name": "lambdaC", "description": "Compton wavelength", "value": 2.42631023538E-12, "uncertainty": 7.6E-22, "exact": false, "unit": "m", "category": "atomic"}, {"name": "Eh", "description": "Hartree energy", "value": 4.359744722206E-18, "uncertainty": 4.8E-30, "exact": false, "unit": "J", "category": "atomic"}, {"name": "ge", "description": "electron g factor", "value": -2.00231930436092, "uncertainty": 3.6E-13, "exact": false, "unit": "", "category": "atomic"}, {"name": "mue", "description": "electron magnetic moment", "value": -9.2847646917E-24, "uncertainty": 2.9E-33, "exact": false, "unit": "J T^-1", "category": "atomic"}, {"name": "mup", "description": "proton magnetic moment", "value": 1.41060679545E-26, "uncertainty": 6.0E-36, "exact": false, "unit": "J T^-1", "category": "atomic"}, {"name": "mec2", "description": "electron mass energy equivalent in MeV", "value": 0.51099895069, "uncertainty": 1.6E-10, "exact": false, "unit": "MeV", "category": "atomic"}, {"name": "mpc2", "description": "proton mass energy equivalent in MeV", "value": 938.27208943, "uncertainty": 2.9E-7, "exact": false, "unit": "MeV", "category": "atomic"} ]
Universal constants
admin
const list "universal"
mentdb
[ {"name": "c", "description": "speed of light in vacuum", "value": 2.99792458E8, "uncertainty": 0, "exact": true, "unit": "m s^-1", "category": "universal"}, {"name": "h", "description": "Planck constant", "value": 6.62607015E-34, "uncertainty": 0, "exact": true, "unit": "J Hz^-1", "category": "universal"}, {"name": "hbar", "description": "reduced Planck constant", "value": 1.0545718176461565E-34, "uncertainty": 0, "exact": true, "unit": "J s", "category": "universal"}, {"name": "G", "description": "Newtonian constant of gravitation", "value": 6.6743E-11, "uncertainty": 1.5E-15, "exact": false, "unit": "m^3 kg^-1 s^-2", "category": "universal"}, {"name": "mu0", "description": "vacuum magnetic permeability", "value": 1.25663706127E-6, "uncertainty": 2.0E-16, "exact": false, "unit": "N A^-2", "category": "universal"}, {"name": "eps0", "description": "vacuum electric permittivity", "value": 8.8541878188E-12, "uncertainty": 1.4E-21, "exact": false, "unit": "F m^-1", "category": "universal"}, {"name": "Z0", "description": "characteristic impedance of vacuum", "value": 376.730313412, "uncertainty": 5.9E-8, "exact": false, "unit": "ohm", "category": "universal"}, {"name": "k", "description": "Boltzmann constant", "value": 1.380649E-23, "uncertainty": 0, "exact": true, "unit": "J K^-1", "category": "universal"} ]
Electromagnetic constants
admin
const list "electromagnetic"
mentdb
[ {"name": "e", "description": "elementary charge", "value": 1.602176634E-19, "uncertainty": 0, "exact": true, "unit": "C", "category": "electromagnetic"}, {"name": "Phi0", "description": "magnetic flux quantum", "value": 2.0678338484619295E-15, "uncertainty": 0, "exact": true, "unit": "Wb", "category": "electromagnetic"}, {"name": "G0", "description": "conductance quantum", "value": 7.748091729863649E-5, "uncertainty": 0, "exact": true, "unit": "S", "category": "electromagnetic"}, {"name": "KJ", "description": "Josephson constant", "value": 4.835978484169836E14, "uncertainty": 0, "exact": true, "unit": "Hz V^-1", "category": "electromagnetic"}, {"name": "RK", "description": "von Klitzing constant", "value": 25812.807459304513, "uncertainty": 0, "exact": true, "unit": "ohm", "category": "electromagnetic"}, {"name": "muB", "description": "Bohr magneton", "value": 9.2740100657E-24, "uncertainty": 2.9E-33, "exact": false, "unit": "J T^-1", "category": "electromagnetic"}, {"name": "muN", "description": "nuclear magneton", "value": 5.0507837393E-27, "uncertainty": 1.6E-36, "exact": false, "unit": "J T^-1", "category": "electromagnetic"} ]