Answer:
The simple answer is: You start with a motor with permanent magnets and then simply turn the output shaft by hand and you will get current from the power input of the motor. However, there are AC and DC motors. Whether you are using a DC motor to charge a battery or an AC motor to power a tool, you will need to turn it at a precise speed to get results. Specially with AC, because you need to worry about frequency (60 hertz ). You also must turn it in reverse. Maybe somebody can expand on this answer.