6.16 Describe the generation of electricity by the rotation of a magnet within a coil of wire and of a coil of wire within a magnetic field and describe the factors which affect the size of the induced voltage

Most helpful video I've seen in a really long time, which hopefully works....

• Movement of magnet produces electromagnetic force 
• Movement + magnetism = current
• 2 slip rings make contact with 2 brushes with copper or carbon connected to an external circuit
• Coil rotates, one half upwards, other downwards
• This produces current in 1 direction
• As continues rotating, half moving upwards moves downwards, vice versa. This constant change results in AC
• Replacing slip rings with split ring produces DC because it reverses current when it is naturally going to reverse so it produces current in only one direction

More diagrams here