CT: Joule effect and Joule’s law are any of several different physical effects discovered or characterized by English physicist James Prescott Joule. These physical effects are not the same, but all are frequently or occasionally referred to in literature as the “Joule effect” or “Joule law” These physical effects include:
Joule’s first law (Joule heating), a physical law expressing the relationship between the heat generated and current flowing through a conductor.
Joule’s second law states that the internal energy of an ideal gas is independent of its volume and pressure, depending only on its temperature.
Magnetostriction, a property of ferromagnetic materials that causes them to change their shape when subjected to a magnetic field.
The Joule–Thomson effect (during Joule expansion), the temperature change of a gas (usually cooling) when it is allowed to expand freely.
The Gough–Joule effect or the Gow–Joule effect, which is the tendency of elastomers to contract if heated while they are under tension.
S: http://en.wikipedia.org/wiki/Joule_effect (last access: 13 February 2015)
N: 1. Joule (proper name): James Prescott Joule (1818-1889) is a British physicist, famous for his research into electricity and thermodynamics. In 1843 Joule calculated the amount of mechanical work needed to produce an equivalent amount of heat. This quantity was called ‘the mechanical equivalent of heat’.
joule n., unit of electrical energy, 1882, coined in recognition of British physicist James P. Joule (1818-1889).
effect (n): mid-14c., “execution or completion (of an act),” from Old French efet (13c., Modern French effet) “result, execution, completion, ending,” from Latin effectus “accomplishment, performance,” from past participle stem of efficere “work out, accomplish,” from ex- “out” + facere “to do”. From French, borrowed into Dutch, German, Scandinavian.
2. The production of heat due to the passage of electric current through a homogeneous conductor.
3. Joule-Thomson effect, the change in temperature that accompanies expansion of a gas without production of work or transfer of heat. At ordinary temperatures and pressures, all real gases except hydrogen and helium cool upon such expansion; this phenomenon often is utilized in liquefying gases. The phenomenon was investigated in 1852 by the British physicists James Prescott Joule and William Thomson (Lord Kelvin). The cooling occurs because work must be done to overcome the long-range attraction between the gas molecules as they move farther apart.
S: 1. http://www.sciencemuseum.org.uk/onlinestuff/people/james%20prescott%20joule.aspx (last access: 13 February 2015); OED – http://www.etymonline.com/index.php?term=joule; http://www.etymonline.com/index.php?allowed_in_frame=0&search=effect&searchmode=none (last access: 13 February 2015). 2. GDT. 3. EncBrit – http://global.britannica.com/EBchecked/topic/306635/Joule-Thomson-effect (last access: 13 February 2015).