Galvanometer n. : An instrument or apparatus for measuring the intensity of an electric current, usually by the deflection of a magnetic needle.

Example:
How does the Galvanometer respond when the current is steady? When the switch is opened?

Taxonomy
galvanometer, coil, pointer, tangent galvanometer, compass needle, mechanism, scale, magnetic field, instruments, deflection, mirror galvanometer, moving coil, coil of wire, calibrated, needle, pen, geomagnetic field, full scale.

Defination from the web:
... The most sensitive form, the Thompson or mirror galvanometer, was invented by William Thomson (Lord Kelvin) ...