Joule

  • joule
    unit systemsi derived unit
    unit ofenergy
    symbolj 
    named afterjames prescott joule
    conversions
    1 j in ...... is equal to ...
       si base units   kgm2s−2
       cgs units   1×107 erg
       kilowatt hours   2.78×10−7 kw⋅h
       kilocalories (thermochemical)   2.390×10−4 kcalth
       btus   9.48×10−4 btu
       electronvolts   6.24×1018 ev

    the joule (l/ jawl, jool;[1][2][3] symbol: j) is a derived unit of energy in the international system of units.[4] it is equal to the energy transferred to (or work done on) an object when a force of one newton acts on that object in the direction of the force's motion through a distance of one metre (1 newton metre or n⋅m). it is also the energy dissipated as heat when an electric current of one ampere passes through a resistance of one ohm for one second. it is named after the english physicist james prescott joule (1818–1889).[5][6][7]

    in terms firstly of base si units and then in terms of other si units, a joule is defined below (please consider this table for the meaning of symbols):

    symbol meaning
    kg kilogram
    m metre
    s second
    n newton
    pa pascal
    w watt
    c coulomb
    v volt

    one joule can also be defined as the following:

    • the work required to move an electric charge of one coulomb through an electrical potential difference of one volt, or one coulomb-volt (c⋅v). this relationship can be used to define the volt.
    • the work required to produce one watt of power for one second, or one watt-second (w⋅s) (compare kilowatt-hour – 3.6 megajoules). this relationship can be used to define the watt.

    the joule is named after james prescott joule. as with every si unit named for a person, its symbol starts with an upper case letter (j), but when written in full it follows the rules for capitalisation of a common noun; i.e., "joule" becomes capitalised at the beginning of a sentence and in titles, but is otherwise in lower case.

  • history
  • practical examples
  • multiples
  • conversions
  • newton metre and torque
  • watt-second
  • see also
  • notes
  • references

Joule
Unit systemSI derived unit
Unit ofEnergy
SymbolJ 
Named afterJames Prescott Joule
Conversions
1 J in ...... is equal to ...
   SI base units   kgm2s−2
   CGS units   1×107 erg
   kilowatt hours   2.78×10−7 kW⋅h
   kilocalories (thermochemical)   2.390×10−4 kcalth
   BTUs   9.48×10−4 BTU
   electronvolts   6.24×1018 eV

The joule (l/ jawl, jool;[1][2][3] symbol: J) is a derived unit of energy in the International System of Units.[4] It is equal to the energy transferred to (or work done on) an object when a force of one newton acts on that object in the direction of the force's motion through a distance of one metre (1 newton metre or N⋅m). It is also the energy dissipated as heat when an electric current of one ampere passes through a resistance of one ohm for one second. It is named after the English physicist James Prescott Joule (1818–1889).[5][6][7]

In terms firstly of base SI units and then in terms of other SI units, a joule is defined below (please consider this table for the meaning of symbols):

Symbol Meaning
kg kilogram
m metre
s second
N newton
Pa pascal
W watt
C coulomb
V volt

One joule can also be defined as the following:

  • The work required to move an electric charge of one coulomb through an electrical potential difference of one volt, or one coulomb-volt (C⋅V). This relationship can be used to define the volt.
  • The work required to produce one watt of power for one second, or one watt-second (W⋅s) (compare kilowatt-hour – 3.6 megajoules). This relationship can be used to define the watt.

The joule is named after James Prescott Joule. As with every SI unit named for a person, its symbol starts with an upper case letter (J), but when written in full it follows the rules for capitalisation of a common noun; i.e., "joule" becomes capitalised at the beginning of a sentence and in titles, but is otherwise in lower case.