What's the difference between i.e. and e.g.?
An instrument that detects small electric currents and indicates their direction and relative strength. Current flowing through the galvanometer passes through a coil near a magnetized needle on a pivot; the strength of the current in the coil regulates the strength of a magnetic field that displaces the needle. Galvanometers can be used directly as ammeters, and are the core element of many ohmmeters and voltmeters.