Joule: Difference between revisions

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'''Joule''' is a unit of energy in the International System of Units. It is equal to the energy transferred to 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. 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.
{{DISPLAYTITLE:Joule}}


==Definition==
== Joule ==
The joule is named after James Prescott Joule. As with every International System of Units (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.
[[File:Definición_del_Joule.svg|thumb|right|Diagram illustrating the definition of a joule.]]
The '''joule''' (symbol: J) is the [[SI unit]] of [[energy]], [[work]], or [[amount of heat]]. It is named after the English physicist [[James Prescott Joule]]. One joule is defined as the amount of energy transferred when a force of one [[newton]] is applied over a distance of one [[meter]].


==Practical examples==
== Definition ==
One joule in everyday life represents approximately:
The joule is defined as:
* The energy required to lift a small apple (102 g) vertically through one metre of air.
* The heat required to raise the temperature of 1 g of water by 0.24 K.
* The amount of electricity required to light a 1 W LED for 1 s.


==Multiples==
: 1 J = 1 N·m = 1 kg·m_/s_
For additional examples, see [[Orders of magnitude (energy)]].


==Conversions==
This means that one joule is equivalent to one [[newton]] of force causing a displacement of one [[meter]]. It can also be expressed in terms of other [[SI base units]] as one kilogram meter squared per second squared.
One joule is the equivalent of one watt of power radiated or dissipated for one second.


In terms of scientific units, one joule is approximately:
== Applications ==
* 6.242×10^18 eV (electronvolts)
The joule is used in various fields of [[science]] and [[engineering]] to quantify [[energy]], [[work]], and [[heat]]. It is commonly used in [[physics]] to describe the energy of moving objects, in [[thermodynamics]] to measure heat transfer, and in [[electrical engineering]] to quantify electrical energy.
* 0.239 cal (calories, or "small calories")
* 0.000948 BTU (British thermal units)


==See also==
== Related Units ==
* [[Conversion of units of energy]]
The joule is related to other units of energy, such as the [[calorie]], [[electronvolt]], and [[watt-hour]].
* [[Orders of magnitude (energy)]]
 
* [[James Prescott Joule]]
* 1 [[calorie]] ≈ 4.184 J
* 1 [[electronvolt]] (eV) ≈ 1.602 _ 10___ J
* 1 [[watt-hour]] (Wh) = 3600 J


==References==
== Historical Context ==
<references />
The joule is named after [[James Prescott Joule]], who studied the nature of heat and discovered its relationship to mechanical work, leading to the formulation of the [[first law of thermodynamics]]. His experiments in the 1840s established the mechanical equivalent of heat, which laid the foundation for the concept of energy conservation.


==External links==
== See Also ==
* [http://www.npl.co.uk/reference/faqs/what-is-a-joule-(faq-energy) What is a joule?]
* [[Energy conservation]]
* [[First law of thermodynamics]]
* [[Newton (unit)]]
* [[Watt]]
 
== Related Pages ==
* [[James Prescott Joule]]
* [[SI base units]]
* [[Thermodynamics]]


[[Category:SI units]]
[[Category:Units of energy]]
[[Category:Units of energy]]
[[Category:James Prescott Joule]]
[[Category:SI derived units]]
 
{{Energy-stub}}

Latest revision as of 10:50, 15 February 2025


Joule[edit]

Diagram illustrating the definition of a joule.

The joule (symbol: J) is the SI unit of energy, work, or amount of heat. It is named after the English physicist James Prescott Joule. One joule is defined as the amount of energy transferred when a force of one newton is applied over a distance of one meter.

Definition[edit]

The joule is defined as:

1 J = 1 N·m = 1 kg·m_/s_

This means that one joule is equivalent to one newton of force causing a displacement of one meter. It can also be expressed in terms of other SI base units as one kilogram meter squared per second squared.

Applications[edit]

The joule is used in various fields of science and engineering to quantify energy, work, and heat. It is commonly used in physics to describe the energy of moving objects, in thermodynamics to measure heat transfer, and in electrical engineering to quantify electrical energy.

Related Units[edit]

The joule is related to other units of energy, such as the calorie, electronvolt, and watt-hour.

Historical Context[edit]

The joule is named after James Prescott Joule, who studied the nature of heat and discovered its relationship to mechanical work, leading to the formulation of the first law of thermodynamics. His experiments in the 1840s established the mechanical equivalent of heat, which laid the foundation for the concept of energy conservation.

See Also[edit]

Related Pages[edit]