Galvanometer

tangent galvanometernull detectorgalvanoscopemeter movementastatic galvanometerballistic galvanometerd'Arsonval galvanometerD'Arsonval movementD'Arsonval/WestonD'Arsonval–Weston
A galvanometer is an electromechanical instrument used for detecting and indicating an electric current.wikipedia
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Ammeter

microammetermoving coil meterampere-meter
Early galvanometers were not calibrated, but their later developments were used as measuring instruments, called ammeters, to measure the current flowing through an electric circuit.
The tangent galvanometer was used to measure currents using this effect, where the restoring force returning the pointer to the zero position was provided by the Earth's magnetic field.

Frog galvanoscope

frog's leg galvanoscoperheoscopic frog
André-Marie Ampère, who gave mathematical expression to Ørsted's discovery and 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.
In modern usage a galvanometer is a sensitive laboratory instrument for measuring current, not voltage.

Electric current

currentcurrentselectrical current
A galvanometer is an electromechanical instrument used for detecting and indicating an electric current. A tangent galvanometer is an early measuring instrument used for the measurement of electric current.
Electric current can be directly measured with a galvanometer, but this method involves breaking the electrical circuit, which is sometimes inconvenient.

Light meter

exposure metermeteringExposure meter calibration
Galvanometers also had widespread use as the visualising part in other kinds of analog meters, for example in light meters, VU meters, etc., where they were used to measure and display the output of other sensors.
They indicate the exposure either with a needle galvanometer or on an LCD screen.

Laser engraving

laser markinglaser engravedetching
Closed-loop mirror galvanometers are also used in similar ways in stereolithography, laser sintering, laser engraving, laser beam welding, laser TVs, laser displays and in imaging applications such as retinal scanning with Optical Coherence Tomography (OCT).
In the third method, both the laser and workpiece are stationary and galvo mirrors move the laser beam over the workpiece surface.

Laser lighting display

laser showlight showlaser light show
Closed-loop mirror galvanometers are also used in similar ways in stereolithography, laser sintering, laser engraving, laser beam welding, laser TVs, laser displays and in imaging applications such as retinal scanning with Optical Coherence Tomography (OCT).
Laser scanners reflect the laser beam on small mirrors which are mounted on galvanometers to which a control voltage is applied.

Laser scanning

laser scannerlaser scanlaser scanned
Mirror galvanometer systems are used as beam positioning or beam steering elements in laser scanning systems.
Additionally, the mirrors can lead to a periodic motion - like the rotating mirror polygons in a barcode scanner or so-called resonant galvanometer scanners - or to a freely addressable motion, as in servo-controlled galvanometer scanners.

Luigi Galvani

GalvaniGalvani, LuigiAloysius Galvani
André-Marie Ampère, who gave mathematical expression to Ørsted's discovery and 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.
Galvani's name also survives as a verb in everyday language (galvanize) as well as in more specialized terms: Galvanic cell, Galvani potential, galvanic corrosion, the galvanometer, galvanization, and Galvanic skin response.

Jacques-Arsène d'Arsonval

d'ArsonvalJacques A. d'ArsonvalJacques Arsene d'Arsonval
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.
Jacques-Arsène d'Arsonval (June 8, 1851 – December 31, 1940) was a French physician, physicist, and inventor of the moving-coil D'Arsonval galvanometer and the thermocouple ammeter.

Ohm's law

ohmicOhmohmic losses
The ability to measure quantitatively voltage and current allowed Georg Ohm, in 1827, to formulate Ohm's Law – that the voltage across a conductor is directly proportional to the current through it.
where x was the reading from the galvanometer, l was the length of the test conductor, a depended on the thermocouple junction temperature, and b was a constant of the entire setup.

Resistor

Resistor controlresistorsResistance
This is generally done by placing a resistor in series with the meter coil.
A simple ohmmeter may apply a voltage from a battery across the unknown resistor (with an internal resistor of a known value in series) producing a current which drives a meter movement.

Measuring instrument

instrumentscientific instrumentinstruments
A tangent galvanometer is an early measuring instrument used for the measurement of electric current.
Galvanometer

Chart recorder

pen recorderchart-recorderpaper chart
In analog strip chart recorders such as used in electrocardiographs, electroencephalographs and polygraphs, galvanometer mechanisms were used to position the pen.
One form of sensitive and high-speed recorder used beams of ultraviolet light reflected off mirror galvanometers, directed at light-sensitive paper.

Johann Schweigger

SchweiggerSchweigger, Johann Salomo Christoph
The earliest galvanometer was reported by Johann Schweigger at the University of Halle on 16 September 1820.
In 1820 he built the first sensitive galvanometer, naming it after Luigi Galvani.

Mirror galvanometer

galvanometer scannersgalvanometricreflecting galvanometer
The most sensitive form, the Thomson or mirror galvanometer, was patented in 1858 by William Thomson (Lord Kelvin) as an improvement of an earlier design invented in 1826 by Johann Christian Poggendorff.
In modern times, high-speed mirror galvanometers are employed in laser light shows to move the laser beams and produce colorful geometric patterns in fog around the audience.

Laser video display

laser TVLaserlaser projectors
Closed-loop mirror galvanometers are also used in similar ways in stereolithography, laser sintering, laser engraving, laser beam welding, laser TVs, laser displays and in imaging applications such as retinal scanning with Optical Coherence Tomography (OCT).
It reflects off of a curved mirror onto a galvanometer-mounted mirror which provides the vertical refresh.

Electric charge

chargechargedelectrical charge
A ballistic galvanometer is a type of sensitive galvanometer for measuring the quantity of charge discharged through it. In reality it is an integrator, unlike a current-measuring galvanometer, the moving part has a large moment of inertia that gives it a long oscillation period.
The quantity of electric charge can be directly measured with an electrometer, or indirectly measured with a ballistic galvanometer.

Leopoldo Nobili

The astatic galvanometer was developed by Leopoldo Nobili in 1825.
In 1825 he developed the astatic galvanometer.

Claude Pouillet

Pouillets
It was first described by Claude Pouillet in 1837.
In his studies of electricity, he designed sine and tangent galvanometers.

Electromechanics

electromechanicalelectro-mechanicalelectromechanical engineering
A galvanometer is an electromechanical instrument used for detecting and indicating an electric current.

Actuator

actuatorsactuatedactuation
A galvanometer works as an actuator, by producing a rotary deflection (of a "pointer"), in response to electric current flowing through a coil in a constant magnetic field.

Electromagnetic coil

coilwindingcoils
A galvanometer works as an actuator, by producing a rotary deflection (of a "pointer"), in response to electric current flowing through a coil in a constant magnetic field.

Magnetic field

magnetic fieldsmagneticmagnetic flux density
A galvanometer works as an actuator, by producing a rotary deflection (of a "pointer"), in response to electric current flowing through a coil in a constant magnetic field.

André-Marie Ampère

AmpèreAmpereAmpère, André-Marie
André-Marie Ampère, who gave mathematical expression to Ørsted's discovery and 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.

Transatlantic telegraph cable

transatlantic cableAtlantic cabletransatlantic cables
For example, 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.