Physics. [Named 1882, after Dr. J. P. Joule, an English physicist.] An electrical unit, being the amount of work done (or of heat generated) by a current of one ampère acting for one second against a resistance of one ohm.
1882. Athenæum, 26 Aug., 274/2. Dr. Siemens proposes to add to these [electrical] units four new ones, as follows: (1) a Watt … (2) a Weber … (3) a Gauss … (4) a unit of heat, to be called a ‘Joule,’ and to be defined as the quantity of heat generated by an ampère flowing through an ohm for one second. Ibid., 2 Sept., 310/2. Two of his units were unanimously approved—namely, (1) the watt … (2) the joule.
Hence Joulemeter, a meter in which the Joule is used as the unit of work or energy. Also Joule’s equivalent, mechanical equivalent of heat: see EQUIVALENT sb. 3 c.
