ammeter

Instrument that measures electric current (flow of charge per unit time), usually in amperes, through a conductor. It should not be confused with a voltmeter, which measures potential difference between two points in a circuit. The ammeter is placed in series (see series circuit) with the component through which current is to be measured, and is constructed with a low internal resistance in order to prevent the reduction of that current as it flows through the instrument itself. A common type is the moving-coil meter, which measures direct current (DC), but can, in the presence of a rectifier (a device which converts alternating current to direct current), measure alternating current (AC) also. Hot-wire, moving-iron, and dynamometer ammeters can be used for both DC and AC.