Video transcription

Hi, I'm Steve Jones, and I'm going to explain how to change the rotation of an electric motor. Now, electric motor has basically two major components, the armature, and the field coils. So, the armature is a coil wrapped on some kind of former in which there is a current being carried, so there's a current going into there. And we have two field coils. Those field coils could either be electro-magnets; that is from electricity, using electricity, or permanent magnets, in which case they are just pieces of magnetic material. In small motors they're more likely to be permanent magnets. In large motors they tend to be electric magnets, electro-magnets. So, how do we change the rotation? Well, by changing the rotation we might want to reverse the direction of the motor. This can be done by changing the direction of the current, or changing the direction of the magnets. That's one simple thing. It doesn't always work, and in AC, in alternating current motors we tend to use a gear box to change the direction of the motor. But to change the rotation we might want to make it rotate faster, in which case we can increase the strength of the magnets by increasing the current into the magnet. That is the way we do that. And we can also increase the current in the armature, so this current in the armature and the current in the field coils. Sometimes it is the same circuit, it is the same current in both in electric motors particularly, in the in the larger electric motors, for example, in your electric drill, OK? Finally, if we want to increase the strength of the magnetism in the armature we make sure the armature is wrapped on a magnetic material on iron, so this would be an iron or steel coil. It also makes it heavy, and makes the motor work more smoothly. So basically, for changing the rotation on an electric motor these are the different things which we can do.