The joule, symbol J, is a unit of energy, work, or amount of heat.

It is equal to the energy expended (or work done) in applying a force of one newton through a distance of one metre (1 newton metre or N·m),

It is also equal to the energy expended (or work done) in passing an electric current of one ampere through a resistance of one ohm for one second.

It is named after the English physicist James Prescott Joule (1818–1889).