Question: Can you explain fully how an electric motor works?

Sam Vinko answered on 12 Mar 2012:

Well, there are many different kinds, but in general to make an electric motor you need an alternating electric current, an electro-magnet (something that becomes a magnet when you let a current flow through it – a solenoid for example) and a shaft made from a magnetic material, like iron, whch can only rotate around a point.

As the current flows through the magnet, a magnetic field is created. Since the shaft is magnetic it will want to align with the field, so a misalignment will cause it to rotate towards the opposite pole – think of a compass aligning with the magnetic field of the Earth. Now, the trick is that before the shaft aligns completely with the field, the current in the electro-magnet is inverted, swapping the north and south poles of the magnet. This places the shaft out of alignment again so it continues to rotate. Every time it gets close to alignment the poles in the magnet are inverted, so the shaft rotates continuously.

Try doing this by hand with a compass and a permanent magnet and make the needle spin!