How does power generator works ?

Click here:

HowStuffWorks "Generators" (http://science.howstuffworks.com/electricity2.htm)

Hello rpieda

An electromotor is a magnet or an electromagnet moving in an electromagnetic field.

If you turn that around and turn a magnet or a magnetic field inside a coil or set of coils, the coil produces electricity. That system is basically called a generator.