joule (J)

The joule (J) is a derived unit of energy in the SI system of units. It is named after the English physicist James Joule. 1 joule is the energy used (or the work done) by a force of one newton in moving its point of application one meter in the direction of the force; also equivalent to the energy dissipated by 1 watt in one second, it equals 107 erg in CGS units. In older units, 1 Btu = 1,055 joules; 1 joule per second = 0.737 ft-lb/s.


One joule is also the work done when a one ampere current is passed through a resistance of one ohm for one second.