What is a galvanometer?

   Galvanometer is an instrument for measuring an electric current or to show when a current has been reduced to a minimum. Most galvanometers depend upon the force produced when a current flows through a wire within a magnetic field. The d'Arsonval galvanometer is one of the best known. It consists of a permanent horseshoe magnet and a rectangular coil suspended in the strong magnetic field between the poles of the magnet. A current passing through the coil causes it to turn in the field.