André-Marie Ampère, who gave mathematical expression to Ørsted's discovery, named the instrument after the Italian electricity researcher Luigi Galvani, who in 1791 discovered the principle of the frog galvanoscope – that electric current would make the legs of a dead frog jerk. Galvanometers have been essential for the development of science and technology in many fields.
The term "galvanometer," in common use by 1836, was derived from the surname of Italian electricity researcher Luigi Galvani, who in 1791 discovered that electric current would make a dead frog's leg jerk. ===Poggendorff and Thomson=== Originally, the instruments relied on the Earth's magnetic field to provide the restoring force for the compass needle.
For example, in the 1800s they enabled long-range communication through submarine cables, such as the earliest transatlantic telegraph cables, and were essential to discovering the electrical activity of the heart and brain, by their fine measurements of current. Galvanometers have also been used as the display components of other kinds of analog meters (e.g., light meters and VU meters), capturing the outputs of these meters' sensors.
Galvanometers can be thought of as a kind of actuator. Galvanometers came from the observation, first noted by Hans Christian Ørsted in 1820, that a magnetic compass's needle deflects when near a wire having electric current.
Strip chart recorders with galvanometer driven pens may have a full-scale frequency response of 100 Hz and several centimeters of deflection. ==History== ===Hans Christian Ørsted=== The deflection of a magnetic compass needle by the current in a wire was first described by Hans Christian Ørsted in 1820.
The phenomenon was studied both for its own sake and as a means of measuring electric current. ===Schweigger and Ampère=== The earliest galvanometer was reported by Johann Schweigger at the University of Halle on 16 September 1820.
Developed by Leopoldo Nobili in 1825, it consists of two magnetized needles parallel to each other but with the magnetic poles reversed.
Later instruments of the "astatic" type used opposing magnets to become independent of the Earth's field and would operate in any orientation. An early mirror galvanometer was invented in 1826 by Johann Christian Poggendorff.
It was first described by Johan Jacob Nervander in 1834 (see J.J.
Nervander, “Mémoire sur un Galvanomètre à châssis cylindrique par lequel on obtient immédiatement et sans calcul la mesure de l’intensité du courant électrique qui produit la déviation de l’aiguille aimantée,” Annales de Chimie et de Physique (Paris), Tome 55, 156–184, 1834.
The term "galvanometer," in common use by 1836, was derived from the surname of Italian electricity researcher Luigi Galvani, who in 1791 discovered that electric current would make a dead frog's leg jerk. ===Poggendorff and Thomson=== Originally, the instruments relied on the Earth's magnetic field to provide the restoring force for the compass needle.
3, pp. 16–23, June 2008.) and in 1837 by Claude Pouillet. A tangent galvanometer consists of a coil of insulated copper wire wound on a circular non-magnetic frame.
Thomson's mirror galvanometer was an improvement of a design invented by Hermann von Helmholtz in 1849.
The mirror galvanometer was used as the receiver in the first trans-Atlantic submarine telegraph cables in the 1850s, to detect the extremely faint pulses of current after their thousand-mile journey under the Atlantic.
The most sensitive form of astatic galvanometer, the Thomson galvanometer, for which Thomson coined the term mirror galvanometer, was patented in 1858 by William Thomson (Lord Kelvin).
In 1882 Jacques-Arsène d'Arsonval and Marcel Deprez developed a form with a stationary permanent magnet and a moving coil of wire, suspended by fine wires which provided both an electrical connection to the coil and the restoring torque to return to the zero position.
By 1888, Edward Weston had patented and brought out a commercial form of this instrument, which became a standard electrical equipment component.
Since the 1980s, galvanometer-type analog meter movements have been displaced by analog-to-digital converters (ADCs) for many uses.
3, pp. 16–23, June 2008.) and in 1837 by Claude Pouillet. A tangent galvanometer consists of a coil of insulated copper wire wound on a circular non-magnetic frame.
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