The other is a shunt across the terminals of the armature.
The magnetic shunt (which is connected Magnetic across the receiving instrument) consists of a low resist- shunt.
It is also necessary to notice that shunt instruments cannot be used for high frequencies, as then the relative inductance of the shunt and wire becomes important and affects the ratio in which the current is divided, whereas for low frequency currents the inductance is unimportant.
In the case of ammeters intended for very small currents, the whole current can be sent through the coil, but for larger currents it is necessary to provide in the instrument a shunt which carries the main current, the movable coil being connected to the ends of this shunt so that it takes a definite small fraction of the current passed through the instrument.
This shunt is generally a strip of platinoid or constantin, and the working wire itself is of the same metal.