I have to do a poster on a van de graaff generator but I am having trouble understanding the concept of it. Here's how I understand it:

The lower roller turns the belt and creates a negative charge while the belt creates a positive charge but after that is where I get confused...can someone explain the rest in a quick easy way.

This web site should help. Be sure to click "next page" and the videos.

http://science.howstuffworks.com/vdg.htm