See also: Thomson

Sir William Thomson (1824 - 1907), better known as a Lord Kelvin , was a British physicist born in Ireland.

One of the innovations of this thermodynamician, is the invention of an absolute zero corresponding to the absolute absence of heat and the absolute absence of pressure of a gas, of which he had noticed the dependant variations according to a linear report/ratio. It left its name to the scale of temperature, known as absolute, or temperature “thermodynamic”, noted T, and measured in Kelvin S (international abbreviation: K and not °K).

Scale Kelvin of the temperatures

Recall of Thermometry: The ordinary scale known as Celsius temperature is, by definition, the absolute temperature shifted in origin of 273,15 K:

T = θ + 273,15

with θ the temperature in °C and T the temperature in °K

The absolute zero is thus located at -273,15 °C

the intervals of the scale of the degree Celsius are thus identical to those of the Kelvin.

The scale Fahrenheit is a Anglo-Saxon scale closely connected of the Celsius scale:

you = 32 + 1,8 T

with T the temperature in °C and you the temperature in °F.

The reverse of the temperature is a parameter which often intervenes in the formulas. The physicists thus use sometimes the parameter

β = 1 ( k_B · T )

where k_B is the Boltzmann constant.

Each scale has its advantage, and this is why their existences remain.

Second principle of thermodynamics

The Second principle of thermodynamics, stated known as of Thomson, is:

That is to say a cycle monotherme. It cannot be driving.

That prohibited the assumption of the perpetual driving of second species, whose traditional image presented to the students is the following one: the sea with 15°C is a potential energy reserve fantastic, if one could draw a work from it: a ship would advance thus, leaving behind him a colder water wake. But that is interdict under the terms of this second principle.

Its studies of thermal conduction made him find a time of cooling of the Earth, extraordinarily short, which, without consolidating the biblical studies, was nevertheless incompatible with work of Charles Lyell (1797-1875), founder of the “geological layers”. So he was badly considered by the pro-Darwiniens. One needed the discovery of radioactive energy to solve the paradox.

Electricity

These same studies enabled him to study the electric conduction of the underwater cables: he is promoter of the great construction of the first transatlantic cable. On the other hand, it ran up against the studies of Maxwell on ether: he refused with the idea of a “transverse” propagation, without “longitudinal” propagation, in this medium. Its study of the influence of the temperature on electric conduction also enabled him to discover the Effet Thomson, as well as the relation between the Peltier effect and the Seebeck effect, at the base of the Thermoélectricité.

He is also the inventor of a simple and cheap mechanism of static electrical production by influence, named the Replenisher (general diagram of the replenisher).

Mechanics

One finds his trace in many theorems known as of Thomson, where the Formule of Stokes intervenes. Its memories will contribute much to the purification of the theory of the Vortex, which, like a jewel, the vectorial Analyze will leave of Gibbs (1839-1903): the vectors are so familiar nowadays that is occulted a little.

Nuclear physicist, it had an original vision of the theory of the atoms containing Nœud S, vortex and Quaternion S, remarkable theory, but without exit.

He was prize winner of the Royal Medal in 1856, of the Médaille Copley in 1883 and chair Royal Society of 1890 1895.

See too

Articles connected

• Physical
• Kelvinator, a company of refrigerators named in its honor

External bonds

• Short film on the propagation of the life according to Lord Kelvin (in)

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