galvanometern

A galvanometer, also known as galvanometern in Swedish, is an instrument for detecting and measuring electric current. It operates on the interaction between a current-carrying coil and a magnetic field, producing a torque that is proportional to the current. The coil is mounted to allow rotation, and a pointer attached to the coil deflects over a calibrated scale. Damping by air or a viscous medium yields a stable reading.

There are several main types. The moving-coil galvanometer, or D'Arsonval galvanometer, uses a rectangular coil in a strong, uniform magnetic field to achieve high sensitivity. The moving-iron galvanometer relies on magnetic attraction to a piece of iron and is robust but typically has a non-linear scale. The ballistic galvanometer is designed to measure the total charge delivered by a current pulse by integrating current over time.

Construction and operation typically involve a coil, a magnetic field produced by a permanent magnet or electromagnet, a restoring mechanism such as a torsion or compression spring, and a damping system. Readings are often conveyed by a pointer on a dial or, in more modern variants, by a microprocessor-based display. In practice, galvanometers have been used as stand-alone instruments and as the sensing elements inside voltmeters, with a series resistor to extend the usable range. Modern electronics have largely replaced many traditional galvanometers, but the basic principle remains foundational in current sensing.

History and etymology reflect the instrument’s purpose: early 19th-century developments led to progressively more sensitive devices, with the moving-coil design introduced by Jacques-Arsène d’Arsonval in the 1880s. The name derives from galvanic phenomena associated with Luigi Galvani, and the term has persisted in both scientific and technical usage.