Energy Conversion refers to the ratio between the output and input of an energy conversion
machine in terms of energy only. The useful output may be electric power, mechanical work,
or heat. It is the process of changing energy from one form to another.
According to the law of conservation of energy, the total energy of a system remains constant, though energy may transform into another form. Two billiard balls colliding, for example, may come to rest, with the resulting energy becoming sound and perhaps a bit of heat at the point of collision.
The SI unit of energy is the joule (J) or newton-meter (N * m). The joule is also the SI unit of work.
1 attojoule = 2.39005736 × 10-19 calories
P = IE
P = Power (Watts)
I = Current (Amps)
E = Voltage (Volts)
So: I= P/E
E = P/I
1 Watt = 1 Ampere * 1 Volt