All About Circuits is an online textbook covering electricity and electronics. Topics covered include: Basic Concepts of Electricity’ OHM’s Law; Electrical Safety; Series and Parallel Circuits; Physics of Conductors and Insulators; Solid-State Device Theory; Binary Arithmetic; Logic Gates; Switches; Digital Storage? It is a great resource. Enjoy.

Related: Textbook Revolution – Open Access Education Materials – High-quality Curricula and Education Resources for Teachers – Online Mathematics Textbooks