# How to produce rotating movement electromagnetically with a coil and with a permanent magnet?

I would like to know this:

To produce rotational motion by eletromagnetism, there are several ways and systems of doing it, but lets say I want to create rotational motion using a permanent magnet and a coil. The fixed magnet creates a constant magnetic field, and the coil, when current goes through it, creates a magnetic field, but this magnetic field has to change directions to create rotational motion, and it happens because current must change directions as well.

I know how it works, I've seen it, there are 2 brushes that current goes to and creates magnetic field. And there are 2 coils on the outside. So it doesn't matter if it is AC or DC, ok.

My question is because theoretically rotational motion is created if magnetic field changes direction, and I was wondering what would make it change direction.

If current must change directions, would it be used AC or DC to create rotational motion? Intuitively, It makes me think AC is always alternating directions and DC don't, so it would be AC.

So tools like eletric motors, drills, mixers, etc etc, use specifically Alternate Current or Direct Current?

And what current do speakers need to work?

• Happy birthday, but do some research yourself tomorrow :) one answer, nearly all power tools use a "universal" brushmotor that doesn't care if it gets AC or DC.
– user108787
Aug 6, 2016 at 10:54
• @count_to_10 but I know how's the brushmotor, I specified the situation because it's hard to find it on the internet. Aug 6, 2016 at 10:58
• AC and DC are basically different ways to carry power, AC is what goes through the high voltage power lines, as it's far more efficient , but at the end of the line, if a device needs DC, there is an inverter built in to the device to change AC to DC. What do you mean by how's the brushmotor, are you asking how does it work?
– user108787
Aug 6, 2016 at 11:01
• @count_to_10 I was saying I know how it works, I've seen it, there are 2 brushes that current goes to and creates magnetic field. And there are 2 coils on the outside. Well, so it doesn't matter if it is AC or DC, ok.. The question was because theoretically rotational motion is created if magnetic field changes direction, and I was wondering what would make it change direction Aug 6, 2016 at 11:05
• @count_to_10 no problem :) Aug 6, 2016 at 11:09