Ammeter

An Ammeter is a measuring instrument used to measure the flow of electric current in a circuit?. The most common implementation uses magnetic? deflection, where increased current passing through a coil causes a small magnet to be increasingly deflected. The deflective force operates against a spirally wound spring such that instrument reurns to zero when the current is switched off.

Because the device is extremely sensitive to small currents and yet needs to be [in circuit]? with the current in order to measure it, ammeters are usually built to measure say 100 milli-amps and can measure larger currents though the use of a shunt? placed in parallel with the meter in the circuit. With this solution, large currents can be measured with only a fraction of the current passing through the meter.