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The joule (/ dʒuːl / JOOL, or / dʒaʊl / JOWL; symbol: J) is the unit of energy in the International System of Units (SI). [1] It is equal to the amount of work done when a force of one newton displaces a mass through a distance of one metre in the direction of that force. It is also the energy dissipated as heat when an electric current of ...
James Prescott Joule FRS FRSE (/ dʒuːl /; [1][2][a] 24 December 1818 – 11 October 1889) was an English physicist, mathematician and brewer, born in Salford, Lancashire. Joule studied the nature of heat, and discovered its relationship to mechanical work. This led to the law of conservation of energy, which in turn led to the development of ...
The mechanical equivalent of heat was a concept that had an important part in the development and acceptance of the conservation of energy and the establishment of the science of thermodynamics in the 19th century. Its independent and simultaneous discovery by James Prescott Joule and by Julius Robert von Mayer led to a priority dispute.
v. t. e. The first law of thermodynamics is a formulation of the law of conservation of energy in the context of thermodynamic processes. The law distinguishes two principal forms of energy transfer, heat and thermodynamic work, that modify a thermodynamic system containing a constant amount of matter. The law also defines the internal energy ...
The Joule effect (during Joule expansion), the temperature change of a gas (usually cooling) when it is allowed to expand freely. The Joule–Thomson effect, the temperature change of a gas when it is forced through a valve or porous plug while keeping it insulated so that no heat is exchanged with the environment.
Maxwell's demon is a thought experiment that appears to disprove the second law of thermodynamics. It was proposed by the physicist James Clerk Maxwell in 1867. [1] In his first letter, Maxwell referred to the entity as a "finite being" or a "being who can play a game of skill with the molecules". Lord Kelvin would later call it a "demon". [2]
The unit of measurement for energy in the International System of Units (SI) is the joule (J). Forms of energy include the kinetic energy of a moving object, the potential energy stored by an object (for instance due to its position in a field), the elastic energy stored in a solid object, chemical energy associated with chemical reactions, the ...
Energy is defined via work, so the SI unit of energy is the same as the unit of work – the joule (J), named in honour of James Prescott Joule [1] and his experiments on the mechanical equivalent of heat. In slightly more fundamental terms, 1 joule is equal to 1 newton metre and, in terms of SI base units. An energy unit that is used in atomic ...