Physicist and engineer — William Thomson, from 1892 Lord Kelvin (1824–1907), was a British physicist and engineer, born in Belfast and for over half a century a professor at Glasgow. A child prodigy, he entered university at the age of ten and became one of the leading figures of nineteenth-century thermodynamics. In 1848 he introduced the absolute temperature scale, now known as the Kelvin scale, founded on a lower limit, absolute zero, independent of the thermometric substance. He made a decisive contribution to formulating the second law of thermodynamics and, with Joule, discovered the Joule-Thomson effect, which underlies gas refrigeration. He was also a great engineer: he successfully led the laying of the first transatlantic telegraph cable, inventing sensitive measuring instruments and galvanometers, which brought him fame and wealth.

Theories and contributions

  • Absolute temperature scale — Thermodynamic scale with its origin at absolute zero: T(K)=T(C)+273,15T(\mathrm{K}) = T(^\circ\mathrm{C}) + 273{,}15.
  • Second law of thermodynamics — It is impossible for a process to have as its sole result the complete conversion of heat into work (Kelvin statement).
  • Joule-Thomson effect — Temperature change of a real gas expanding at constant enthalpy through a throttle.

Linked atoms

6 linked atoms.

04 Energia e lavoro

08b Termologia

10 Trasformazioni irreversibili e bilancio energetico

12 Cicli e macchine termiche

21 Introduzione alla meccanica quantistica