A device that converts mechanical energy into electric energy. The operation of electric generators is based on the phenomenon of electromagnetic induction — when a conductor moves relative to a magnetic field, voltage is induced in this conductor. If a magnet is spinning inside a coil, alternating current voltage is induced in the coil. Steam turbines, internal combustion engines, gas combustion turbines, electric motors, water turbines, and wind turbines are the common methods to supply the mechanical energy for such devices. Generators are made in a wide range of sizes, from very small machines with a few watts of output power to very large power plant devices providing gigawatts of power.