James Prescott Joule FRS ( /dʒuːl/; 24 December 1818 – 11 October 1889) was an English physicist and brewer, born in Salford, Lancashire. Joule studied the nature of heat, and discovered its relationship to mechanical work (see energy). This led to the theory of conservation of energy, which led to the development of the first law of thermodynamics. The SI derived unit of energy, the joule, is named after him. He worked with Lord Kelvin to develop the absolute scale of temperature, made observations on magnetostriction, and found the relationship between the current through resistance and the heat dissipated, now one of the two laws called Joule's law.
Read more about James Prescott Joule: Early Years, The Mechanical Equivalent of Heat, Reception and Priority, Kinetic Theory, Honours, Selected Writings