I think what you were looking at when you disassembled the ammeter was
the "shunt" wire (which does look quite a bit like a paper clip). The
electromagnet (or coil) is attached to the needle and causes itself and
the needle to move when a current moves through it. Since the meter
carries all of the current coming from the generator or alternator
(upwards of 30 amps, possibly), not all of the current could pass
through the coil without damaging it. (The coil should be small and
light weight so that it can respond rapidly). The shunt is just what
the name says. It is a pathway for most of the current to travel
without passing through the coil and is connected in parallel to the
coil. It is a careful matching of the resistance of the coil and the
shunt which determines the maximum current the ammeter can handle. An
ammeter works on the same principle as an electric motor - pass a
current through a wire embedded in a magnetic field and the wire will
experience a force which can be used to produce a rotation.
Cheers,
Tod
B382002384LRXFE
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