energ@tic -




Square one

Definition of energy

Energy is the ability of a system to produce a work carrying a movement, a light or a heat.
There are various kinds of energy :

  • thermic energy (heat)
  • electric energy
  • chemical energy (in fuel or in batteries, for example)
  • potential energy, due to the gravity
  • kinetic energy, characterized by motion

The unit of measure of energy in the I.S. (International System) is the Joule.

The power of a system is the energy developed by this system by the unit of time. The power is measured in watts (W).
1 Watt = 1 Joule /second.

To measure the energy consumption, we multiply the power by the time: an electric device that works at a power of 1kW during 1 hour consumes 1 kilowatt hour (kWh).
1 kWh = 3,6 MJ (Mega joules).