Galvanometer

A galvanometer directly measure the flow of electric charges through a wire. It is a small pivoting coil of wire in the field of a permanent magnet. The coil is attached to a thin indicating hand that points at a calibrated scale. A tiny spring pulls the coil, and hand to the zero position. In some meters, the magnetic field acts on a small piece of iron to perform the same effect as a spring.

When a current flows through the coil, the coil generates a magnetic field. This field acts with or gainst the permanent magnet. The coil pivots, pushing against the spring, and moving the indicating hand. The hand points at a scale reading the electric current.

Some scales have mirrors next to the markings. The reflection of the hand is more accurate, because there is less parallax error.

Galvanometers have been replaced by analog to digital converters for most uses.

See also electrometer, electricity, electronics, electric current and electric charge.