The name ‘ammeter’ is an abbreviation of ‘ampere meter’. An ampere, or more familiarly, ‘amp’, is the fundamental unit of active electric current. So, just what is an ammeter?
It clearly follows that the function of an ammeter is to measure that current within an electrical circuit. Ammeters measure current in two metrics - ‘draw’, the flow of current in a particular circuit, and ‘continuity’, the steadiness of the current and the presence or absence of interruptions.
Ammeters are used to detect problems in electrical circuits - unusually high or low levels of current, for example. The former can indicate malfunctioning components for a short circuit, while the latter can be a sign of disruptive interruptions or unusual electrical impedance. It is routine to check sockets or outlets using an ammeter when conducting repairs or changing a fuse.
Ammeters are not to be confused with voltmeters, which measure the voltage in a circuit. Voltage, also known as ‘electrical tension’, is the difference in electrical potential between two points in a circuit and therefore the amount of force required to move charge between them.