I like using two simulators from PhET, to teach students about static electricity. The first one is a simulator with balloons and a sweater.
The second is a simulator featuring John Travoltage.
Disclaimer: These simulators can be tricky to use in school settings for two reasons. Sometimes a download is required, and some schools do not allow downloads. You may need to get prior approval from your IT department to use these simulations. Second, PhET simulators sometimes use Flash, which doesn’t work on iPads.