From Conservapedia
Jump to: navigation, search

This page lists various constants used in physics and some useful conversions.

Physical constants

The number in brackets represents the uncertainty in the constant, so that has an uncertainty of .

Name Symbol Value Meaning Used in Exact
Planck's constant It relates the frequency of a photon to its energy Quantum mechanics Inexact[1]
Speed of light This is the speed of light in a vacuum Most of physics, such as optics and relativity Exact[2]
Permittivity of free space Related to the strength of an electric field produced by a charge Electromagnetism Exact[3]
Permeability of free space Related to the strength of magnetic fields produced by a current Electromagnetism Exact[4]
Elementary charge The magnitude of the electric charge on an electron Determines the strength of electric and magnetic fields produced by protons, electrons etc. Inexact[5]
Avogadro's number The number of constituents in 1 mole of something Chemistry, statistical mechanics, thermodynamics Inexact[6]
Ideal gas constant Relates the pressure, volume, temperature and number of moles of an ideal gas Thermodynamics Inexact[7]
Faraday Constant The electric charge on one mole of electrons (Avogadro's number times elementary charge) Chemistry, physics Inexact[8]
Gravitational constant Constant related to the strength of Newtonian gravity Newtonian gravity Inexact[9]
Boltzmann constant Thermodynamics Inexact[10]
Reduced Planck's constant Quantum mechanics It is Planck's constant divided by . Inexact[11]
Wien displacement constant Relates the temperature of a black body to the peak in its spectrum Inexact[12]
Standard acceleration due to gravity This is the acceleration of any object near to the earth's surface when gravity is the only force acting (i.e., no air resistance). Mechanics Exact[13]
Proton mass Rest mass of a proton Inexact[14]
Neutron mass Rest mass of a neutron Inexact[15]
Electron mass Rest mass of an electron Inexact[16]

Useful Conversions


1 metre = 39.37 inches 1 metre = 3.281 feet 1 kilometre = 0.6213 miles

1 mile = 5280 feet 1 mile = 1760 yards


1 kilogram = 35.27 ounce 1 kilogram = 2.205 pounds


1 atm = 101.1 kPa 1 atm = 760 torr 1 atm = 760 mm Hg


Atomic mass unit: 1.00 amu = 1.67 x 10−27 kg

1.000 calorie = 4.184 Joules

Standard Temperature and Pressure (STP): temperature = 273 K and pressure = 1.00 atm

Relative mass and charge of subatomic particles found in atoms.

Atomic particles
Relative Mass Relative Charge
Proton 1 +1
Neutron 1 0
Electron 1/1837 -1


Prefixes in front of a unit indicate that that unit should be multiplied by a multiple of ten, e.g. Giga is 109, so 1 GPa = 109 Pa.

Name Symbol Power
Pico p 10−12
nano n 10−9
micro μ 10−6
milli m 10−3
centi c 10−2
deci d 10−1
deca da 101
hecto h 102
kilo k 103
mega M 106
giga G 109
tera T 1012