 Moving-magnet galvanometer

A moving-magnet galvanometer measures electric current through the torque it exerts on a movable magnetic dipole moment. A fixed coil carries the current and creates a magnetic field; a suspended magnet turns against a restoring torque supplied by its suspension or a reference field.

For sufficiently small deflections in a calibrated geometry, the coil field and resulting angular response are proportional to electric current. A pointer or reflected optical spot reads the angle. This differs from a moving-coil galvanometer, where the current-carrying coil itself moves. Mechanical damping determines whether the indication oscillates or settles smoothly after a current change.