Constants
This page lists various constants used in physics and some useful conversions.
Contents
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
Length
1 metre = 39.37 inches 1 metre = 3.281 feet 1 kilometre = 0.6213 miles
1 mile = 5280 feet 1 mile = 1760 yards
Weight
1 kilogram = 35.27 ounce 1 kilogram = 2.205 pounds
Pressure
1 atm = 101.1 kPa 1 atm = 760 torr 1 atm = 760 mm Hg
Other
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.
Relative Mass | Relative Charge | |
---|---|---|
Proton | 1 | +1 |
Neutron | 1 | 0 |
Electron | 1/1837 | -1 |
Prefixes
Prefixes in front of a unit indicate that that unit should be multiplied by a multiple of ten, e.g. Giga is 10^{9}, so 1 GPa = 10^{9} 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 | 10^{1} |
hecto | h | 10^{2} |
kilo | k | 10^{3} |
mega | M | 10^{6} |
giga | G | 10^{9} |
tera | T | 10^{12} |
References
- ↑ http://physics.nist.gov/cgi-bin/cuu/Value?h
- ↑ http://physics.nist.gov/cgi-bin/cuu/Value?c
- ↑ http://physics.nist.gov/cgi-bin/cuu/Value?ep0
- ↑ http://physics.nist.gov/cgi-bin/cuu/Value?mu0
- ↑ http://physics.nist.gov/cgi-bin/cuu/Value?e
- ↑ http://physics.nist.gov/cgi-bin/cuu/Value?na
- ↑ http://physics.nist.gov/cgi-bin/cuu/Value?r
- ↑ http://ch302.cm.utexas.edu/echem/echem-stoich/echem-stoich-all.php
- ↑ http://physics.nist.gov/cgi-bin/cuu/Value?bg
- ↑ http://physics.nist.gov/cgi-bin/cuu/Value?k
- ↑ http://physics.nist.gov/cgi-bin/cuu/Value?hbar
- ↑ http://physics.nist.gov/cgi-bin/cuu/Value?bwien
- ↑ http://physics.nist.gov/cgi-bin/cuu/Value?gn
- ↑ http://physics.nist.gov/cgi-bin/cuu/Value?mp
- ↑ http://physics.nist.gov/cgi-bin/cuu/Value?mn
- ↑ http://physics.nist.gov/cgi-bin/cuu/Value?me