The Kelvin is a unit of measurement for temperature. It named after the Irish physicist and engineer William Thomson, named baron by the name of Lord Kelvin.
The title of Baron Kelvin was conferred by merit of his discoveries, it comes from the Kelvin River, which flows near its Scottish university of Glasgow where he performed important works in the analysis of electricity mathematics and thermodynamics, and gave a large contribution to unify the emerging discipline of physics. He made his career as an engineer and inventor of the electric telegraph, which gave him a greater consideration from the public opinion and assured him fame and wealth.
By 1847, Thomson had already earned a reputation as an early and maverick scientist when he attended the annual meeting of the “British Association for the Advancement of Science” in Oxford.
Thomson was intrigued but skeptical of the attempt to discredit the caloric theory and the theory of Joule’s heat engine. Although he felt that Joule’s results were in need of a theoretical explanation, he engaged more deeply following the school of Carnot and Clayperon.
In 1848 he extended the Carnot-Clayperon theory still furthe, proposing an absolute temperature scale in which a heat unit that pass from a body A (at temperature T °) to a body B at a temperature (T-1) °,
produces the same mechanical effect regardless of the number T.
“… the conversion of heat (or caloric) into a mechanical effect
is probably impossible,
certainly undiscovered. »
In the published text, Thomson delete the most radical statements and declared that “the whole theory of the motive power of heat is founded on two propositions, respectively due to Joule, and to Carnot and Clausius”. Thomson went on and enunciated a principle of the second version.
“It is impossible, by means of an
inanimate material agent, to obtain a mechanical effect from any portion of matter
by cooling it below the temperature of the
coldest of the surrounding objects”
Thomson supported the theory that heat was a form of motion, but admitted that he was influenced only by the thought of Humphry Davy as well as the experiments of Joule and Julius von Mayer, stating that the experimental demonstration of the conversion of the heat into work was still missing.
The Kelvin is used to measure the hue of light.
This is an important finding in lighting, in fact, depending on the temperature of the used light bulbs we will be faced with different scenarios, which will be perceived by our eyes as more or less hot – or cold – from the point of view of the light shades. So a warm white light (Warm) is between 2700 °K and 3500 °K; a cool white light (Cool) for big department stores is around 4000 °K and up; daytime sunlight (Sunlight) exceeds 5000 °K.