I got a lot from the articles on amasci.com by Bill Beaty. He's done a lot of experimenting, reading, and thinking about this stuff and how to explain it. And is a gifted communicator.
Great essays on understanding electricity, current, voltage, capacitors, transistors, batteries, static electricity etc etc, and popular misconceptions.
Thanks thanks thanks, I read the article about why three prongs long ago. Every now and then I want to say the same article to someone else but did not remember where I read it.
There is also one about different types of plugs in Europe and UK which I cannot find
Articles on Electricity http://amasci.com/ele-edu.html
Great essays on understanding electricity, current, voltage, capacitors, transistors, batteries, static electricity etc etc, and popular misconceptions.