Difference between revisions of "Constants"

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This page lists various constants used in [[physics]] and some useful conversions.
+
This page lists various '''constants''' used in [[physics]] and some useful conversions.
  
 
==Physical constants==
 
==Physical constants==
 
The number in brackets represents the uncertainty in the constant, so that <math>6.626070040(81) \times 10^{-34}</math> has an uncertainty of <math>0.00000000081 \times 10^{-34}</math>.
 
The number in brackets represents the uncertainty in the constant, so that <math>6.626070040(81) \times 10^{-34}</math> has an uncertainty of <math>0.00000000081 \times 10^{-34}</math>.
  
−
{| class="wikitable"
+
{| class="wikitable" style="background: white"
 
|-
 
|-
 
!Name
 
!Name
Line 15: Line 15:
 
|[[Planck's constant]]
 
|[[Planck's constant]]
 
|<math>h</math>
 
|<math>h</math>
−
|<math>6.626070040(81) \times 10^{-34} \,</math> J s
+
|<math>6.626070040(81) \times 10^{-34} \, \mathrm{J} \, \mathrm{s}</math>  
 
|It relates the [[frequency]] of a [[photon]] to its [[energy]]
 
|It relates the [[frequency]] of a [[photon]] to its [[energy]]
 
|[[Quantum mechanics]]
 
|[[Quantum mechanics]]
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|[[Speed of light]]
 
|[[Speed of light]]
 
|<math>c</math>
 
|<math>c</math>
−
|299,792,458 m s<sup>-1</sup>
+
|<math>299,792,458 \, \mathrm{m} \, \mathrm{s^{-1}}</math>
 
|This is the speed of light in a [[vacuum]]
 
|This is the speed of light in a [[vacuum]]
 
|Most of physics, such as [[optics]] and [[relativity]]
 
|Most of physics, such as [[optics]] and [[relativity]]
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|Permittivity of free space
 
|Permittivity of free space
 
|<math>\epsilon_0</math>
 
|<math>\epsilon_0</math>
−
|<math>8.854187817... \times 10^{-12}</math> F m<sup>-1</sup>
+
|<math>8.854187817... \times 10^{-12} \, \mathrm{F} \, \mathrm{m^{-1}}</math>
 
|Related to the strength of an [[electric field]] produced by a charge
 
|Related to the strength of an [[electric field]] produced by a charge
 
|[[Electromagnetism]]
 
|[[Electromagnetism]]
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|Permeability of free space
 
|Permeability of free space
 
|<math>\mu_0</math>
 
|<math>\mu_0</math>
−
|<math>4 \pi \times 10^{-7}</math>
+
|<math>4 \pi \times 10^{-7} \, \mathrm{H} \, \mathrm{m^{-1}}</math>
−
|Related to the strength of [[magnetic field]s produced by a [[current]]
+
|Related to the strength of [[magnetic field]]s produced by a [[current]]
 
|[[Electromagnetism]]
 
|[[Electromagnetism]]
 
|Exact<ref>http://physics.nist.gov/cgi-bin/cuu/Value?mu0</ref>
 
|Exact<ref>http://physics.nist.gov/cgi-bin/cuu/Value?mu0</ref>
Line 43: Line 43:
 
|Elementary charge
 
|Elementary charge
 
|<math>e</math>
 
|<math>e</math>
−
|<math>1.6021766208(98) \times 10^{-19}</math> C
+
|<math>1.6021766208(98) \times 10^{-19} \, \mathrm{C}</math>
 
|The magnitude of the electric charge on an electron
 
|The magnitude of the electric charge on an electron
−
|Determines the strength of electric and magnetic fields produced by [[proton]]s, [[electron]]s etc
+
|Determines the strength of electric and magnetic fields produced by [[proton]]s, [[electron]]s etc.
 
|Inexact<ref>http://physics.nist.gov/cgi-bin/cuu/Value?e</ref>
 
|Inexact<ref>http://physics.nist.gov/cgi-bin/cuu/Value?e</ref>
 
|-
 
|-
 
|[[Avogadro's number]]
 
|[[Avogadro's number]]
 
|<math>N_A</math>
 
|<math>N_A</math>
−
|<math>6.022140857(74) \times 10^{23}</math> mol<sup>-1</sup>
+
|<math>6.022140857(74) \times 10^{23} \, \mathrm{mol^{-1}}</math>
 
|The number of constituents in 1 mole of something
 
|The number of constituents in 1 mole of something
 
|[[Chemistry]], [[statistical mechanics]], [[thermodynamics]]
 
|[[Chemistry]], [[statistical mechanics]], [[thermodynamics]]
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|Ideal gas constant
 
|Ideal gas constant
 
|<math>R</math>
 
|<math>R</math>
−
|<math>8.3144598(48)</math> J mol<sup>-1</sup> K<sup>-1</sup>
+
|<math>8.3144598(48) \, \mathrm{J} \, \mathrm{mol^{-1}} \, \mathrm{K^{-1}}</math>
 
|Relates the [[pressure]], [[volume]], [[temperature]] and number of moles of an [[ideal gas]]
 
|Relates the [[pressure]], [[volume]], [[temperature]] and number of moles of an [[ideal gas]]
 
|[[Thermodynamics]]
 
|[[Thermodynamics]]
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|Faraday Constant
 
|Faraday Constant
 
|<math>F</math>
 
|<math>F</math>
−
|<math>96485 C/mol^-1</math>
+
|<math>96485 \mathrm{C} \, \mathrm{mol^{-1}}</math>
 
|The electric charge on one mole of electrons (Avogadro's number times elementary charge)
 
|The electric charge on one mole of electrons (Avogadro's number times elementary charge)
 
|[[Chemistry]], [[physics]]
 
|[[Chemistry]], [[physics]]
 
|Inexact<ref>http://ch302.cm.utexas.edu/echem/echem-stoich/echem-stoich-all.php</ref>
 
|Inexact<ref>http://ch302.cm.utexas.edu/echem/echem-stoich/echem-stoich-all.php</ref>
 +
|-
 +
|[[Gravitational constant]]
 +
|<math>G</math>
 +
|<math>6.67408(31) \times 10^{-11} \, \mathrm{N} \, \mathrm{m^2} \, \mathrm{kg^{-2}}</math>
 +
|Constant related to the strength of Newtonian gravity
 +
|Newtonian [[gravity]]
 +
|Inexact<ref>http://physics.nist.gov/cgi-bin/cuu/Value?bg</ref>
 +
|-
 +
|Boltzmann constant
 +
|<math>k</math>
 +
|<math>1.38064852(79) \times 10^{-23} \, \mathrm{J} \, \mathrm{K^{-1}}</math>
 +
|[[Thermodynamics]]
 +
|
 +
|Inexact<ref>http://physics.nist.gov/cgi-bin/cuu/Value?k</ref>
 +
|-
 +
|Reduced Planck's constant
 +
|<math>\hbar</math>
 +
|<math>1.054571800(13) \times 10^{-34} \, \mathrm{J} \, \mathrm{s}</math>
 +
|[[Quantum mechanics]]
 +
|It is [[Planck's constant]] divided by <math>2 \pi</math>.
 +
|Inexact<ref>http://physics.nist.gov/cgi-bin/cuu/Value?hbar</ref>
 +
|-
 +
|Wien displacement constant
 +
|<math>b</math>
 +
|<math>2.8977729(17) \times 10^{-3} \, \mathrm{m} \, \mathrm{K}</math>
 +
|Relates the [[temperature]] of a black body to the peak in its spectrum
 +
|
 +
|Inexact<ref>http://physics.nist.gov/cgi-bin/cuu/Value?bwien</ref>
 +
|-
 +
|[[Gravitational constant|Standard acceleration due to gravity]]
 +
|<math>g</math>
 +
|<math>9.80665 \, \mathrm{m} \, \mathrm{s^{-2}}</math>
 +
|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<ref>http://physics.nist.gov/cgi-bin/cuu/Value?gn</ref>
 +
|-
 +
|Proton mass
 +
|<math>m_p</math>
 +
|<math>1.672621898(21) \times 10^{-27} \, \mathrm{kg}</math>
 +
|[[Rest mass]] of a [[proton]]
 +
|
 +
|Inexact<ref>http://physics.nist.gov/cgi-bin/cuu/Value?mp</ref>
 +
|-
 +
|Neutron mass
 +
|<math>m_n</math>
 +
|<math>1.674927471(21) \times 10^{-27} \, \mathrm{kg}</math>
 +
|[[Rest mass]] of a [[neutron]]
 +
|
 +
|Inexact<ref>http://physics.nist.gov/cgi-bin/cuu/Value?mn</ref>
 +
|-
 +
|Electron mass
 +
|<math>m_e</math>
 +
|<math>9.10938356(11) \times 10^{-31} \, \mathrm{kg}</math>
 +
|[[Rest mass]] of an [[electron]]
 +
|
 +
|Inexact<ref>http://physics.nist.gov/cgi-bin/cuu/Value?me</ref>
 
|}
 
|}
  
 
==Useful Conversions==
 
==Useful Conversions==
  
−
1 atm = 101.1 kPa
+
===Length===
  
−
1.000 calorie = 4.184 Joules
+
1 metre = 39.37 inches
 +
1 metre = 3.281 feet
 +
1 kilometre = 0.6213 miles
  
−
1 Calorie = 1000 calories
+
1 mile = 5280 feet
 +
1 mile = 1760 yards
  
−
760 torr = 1 atm
+
===Weight===
  
−
760&nbsp;mm Hg = 1 atm
+
1 kilogram = 35.27 ounce
 +
1 kilogram = 2.205 pounds
  
−
--------
+
===Pressure===
 +
1 atm = 101.1 kPa
 +
1 atm = 760 torr
 +
1 atm = 760&nbsp;mm Hg
  
−
Atomic mass unit: 1.00 amu = 1.67 x <math>10^{-27}</math>kg
+
===Other===
 +
 
 +
Atomic mass unit: 1.00 amu = 1.67 x 10<sup>−27</sup> kg
 +
 
 +
1.000 calorie = 4.184 Joules
  
 
Standard Temperature and Pressure (STP): temperature = 273 K and pressure = 1.00 atm
 
Standard Temperature and Pressure (STP): temperature = 273 K and pressure = 1.00 atm
  
−
---------
+
----
 +
 
 +
Relative [[mass (science)|mass]] and [[charge]] of subatomic particles found in [[atom]]s.
  
 
{| class="wikitable" style="text-align:left"
 
{| class="wikitable" style="text-align:left"
−
|+ Bond Strengths
+
|+ Atomic particles
 
|-
 
|-
−
!  !! Mass !! Charge
+
!  !! Relative Mass !! Relative Charge
 
|-
 
|-
−
| '''Proton''' || 1.67 x <math>10^-27 </math> kg || +1
+
| '''Proton''' || 1 || +1
 
|-
 
|-
−
| '''Neutron''' || 1.67 x <math>10^-27 </math> kg || 0
+
| '''Neutron''' || 1 || 0
 
|-
 
|-
−
| '''Electron''' || 9.11 x <math>10^-31 </math> kg|| -1
+
| '''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<sup>9</sup>, so 1 GPa = 10<sup>9</sup> Pa.
 +
 +
{| class="wikitable"
 +
|-
 +
!Name
 +
!Symbol
 +
!Power
 +
|-
 +
|Pico
 +
|p
 +
|10<sup>−12</sup>
 +
|-
 +
|nano
 +
|n
 +
|10<sup>−9</sup>
 +
|-
 +
|micro
 +
|μ
 +
|10<sup>−6</sup>
 +
|-
 +
|milli
 +
|m
 +
|10<sup>−3</sup>
 +
|-
 +
|centi
 +
|c
 +
|10<sup>−2</sup>
 +
|-
 +
|deci
 +
|d
 +
|10<sup>−1</sup>
 +
|-
 +
|deca
 +
|da
 +
|10<sup>1</sup>
 +
|-
 +
|hecto
 +
|h
 +
|10<sup>2</sup>
 +
|-
 +
|kilo
 +
|k
 +
|10<sup>3</sup>
 +
|-
 +
|mega
 +
|M
 +
|10<sup>6</sup>
 +
|-
 +
|giga
 +
|G
 +
|10<sup>9</sup>
 +
|-
 +
|tera
 +
|T
 +
|10<sup>12</sup>
 +
|}
 
==References==
 
==References==
 
{{reflist}}
 
{{reflist}}

Latest revision as of 02:00, July 17, 2019

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

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.

Atomic particles
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 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

References

  1. ↑ http://physics.nist.gov/cgi-bin/cuu/Value?h
  2. ↑ http://physics.nist.gov/cgi-bin/cuu/Value?c
  3. ↑ http://physics.nist.gov/cgi-bin/cuu/Value?ep0
  4. ↑ http://physics.nist.gov/cgi-bin/cuu/Value?mu0
  5. ↑ http://physics.nist.gov/cgi-bin/cuu/Value?e
  6. ↑ http://physics.nist.gov/cgi-bin/cuu/Value?na
  7. ↑ http://physics.nist.gov/cgi-bin/cuu/Value?r
  8. ↑ http://ch302.cm.utexas.edu/echem/echem-stoich/echem-stoich-all.php
  9. ↑ http://physics.nist.gov/cgi-bin/cuu/Value?bg
  10. ↑ http://physics.nist.gov/cgi-bin/cuu/Value?k
  11. ↑ http://physics.nist.gov/cgi-bin/cuu/Value?hbar
  12. ↑ http://physics.nist.gov/cgi-bin/cuu/Value?bwien
  13. ↑ http://physics.nist.gov/cgi-bin/cuu/Value?gn
  14. ↑ http://physics.nist.gov/cgi-bin/cuu/Value?mp
  15. ↑ http://physics.nist.gov/cgi-bin/cuu/Value?mn
  16. ↑ http://physics.nist.gov/cgi-bin/cuu/Value?me
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