If anyone is attempting their electrical licence, you might be interested in looking at
http://ourworld.compuserve.com/homepages/G_KNOTT This site and available software is written by a Cambridge college teacher and I have to say, is very impressive. It makes light work of learning electrical and electronic theory as it is written in a very easy to understand way. As an avionics engineer, I find the theory serves well as a reminder. For you riggers going for the licence, it will be a great help and its only a tenner. Good investment i`d say.