I have been asked to demonstrate some electrical things to a GCSE student. One of the things on the syllabus is potential difference, and another is EMF – electromotive force. I had always assumed ...

The simplest complete circuit is a piece of wire from one end of a battery to the other. An electric current can flow in the wire from one end of the battery to the other, but nothing useful happens.

Current is a measure of how much electric charge flows through a circuit. The more charge that flows, the bigger the current. Current is measured in amperes. The symbol for ampere is A. For example, ...