What would be measured on a Galvanometer?
"Mirror galvanometer A mirror galvanometer is an electromechanical instrument that indicates that it has sensed an electric current by deflecting a light beam with a mirror. The beam of light projected on a scale acts as a long massless pointer. In 1826, Johann Christian Poggendorff developed the mirror galvanometer for detecting electric currents. The apparatus is also known as a ""spot galvanometer"" after the spot of light produced in some models. Mirror galvanometers were used extensively in scientific instruments before reliable, stable electronic amplifiers were available. The most common uses were as recording equipment for seismometers and submarine cables used"
"heart and brain, by their fine measurements of current. 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. Today the main type of galvanometer mechanism, still in use, is the moving coil, D'Arsonval/Weston type. Modern galvanometers, of the D'Arsonval/Weston type, are constructed with a small pivoting coil of wire, called a spindle, in the field of a permanent magnet. The coil is attached to a thin pointer that traverses a calibrated scale. A"
"Ballistic galvanometer A ballistic galvanometer is a type of sensitive galvanometer; commonly a mirror galvanometer. Unlike a current-measuring galvanometer, the moving part has a large moment of inertia, thus giving it a long oscillation period. It is really an integrator measuring the quantity of charge discharged through it. It can be either of the moving coil or moving magnet type. Before first use the ballistic constant of the galvanometer must be determined. This is usually done by connecting to the galvanometer a known capacitor, charged to a known voltage, and recording the deflection. The constant K is calculated from the"
"They were the first instruments used to detect and measure small amounts of electric currents. 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. Sensitive galvanometers have been essential for the development of science and technology in many fields. 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"
"the thin film. Galvanostat A galvanostat, (also known as amperostat) is a control and measuring device capable of keeping the current through an electrolytic cell in coulometric titrations constant, disregarding changes in the load itself. Its main feature is its ""nearly"" """"infinite"""" (i.e. extremely high in respect to common loads) internal resistance. The designation """"galvanostat"""" is mainly used in electrochemistry: this device differs from common constant current sources by its ability to supply ""and measure"" a wide range of currents (from picoamperes to amperes) of both polarities. The galvanostat responds to changes in the resistance of the cell by varying"
"galvanoscope, frog galvanometer, rheoscopic frog, and frog electroscope. The device is properly called a ""galvanoscope"" rather than ""galvanometer"" since the latter implies accurate measurement whereas a galvanoscope only gives an indication. In modern usage a galvanometer is a sensitive laboratory instrument for measuring current, not voltage. Everyday current meters for use in the field are called ammeters. A similar distinction can be made between electroscopes, electrometers, and voltmeters for voltage measurements. Frogs were a popular subject of experiment in the laboratories of early scientists. They are small, easily handled, and there is a ready supply. Marcello Malpighi, for instance, used"
"for telegraphy. In modern times, the term ""mirror galvanometer"" is also used for devices that move laser beams by rotating a mirror through a galvanometer set-up. The name is often abbreviated as ""galvo"". The mirror galvanometer was later improved by William Thomson, later to become Lord Kelvin. He would patent the device in 1858. Thomson reacted to the need for an instrument that could indicate with sensibility all the variations of the current in a long cable. This instrument was far more sensitive than any which preceded it, enabling the detection of the slightest defect in the core of a"
"Galvanostat A galvanostat, (also known as amperostat) is a control and measuring device capable of keeping the current through an electrolytic cell in coulometric titrations constant, disregarding changes in the load itself. Its main feature is its ""nearly"" """"infinite"""" (i.e. extremely high in respect to common loads) internal resistance. The designation """"galvanostat"""" is mainly used in electrochemistry: this device differs from common constant current sources by its ability to supply ""and measure"" a wide range of currents (from picoamperes to amperes) of both polarities. The galvanostat responds to changes in the resistance of the cell by varying its output potential:"
"the previously unknown resistor. These capabilities to translate different kinds of electric quantities, in to pointer movements, make the galvanometer ideal for turning output of other sensors that outputs electricity (in some form or another), into something that can be read by a human. Because the pointer of the meter is usually a small distance above the scale of the meter, parallax error can occur when the operator attempts to read the scale line that ""lines up"" with the pointer. To counter this, some meters include a mirror along the markings of the principal scale. The accuracy of the reading"
"means of a galvanometer. The sliding contact or wiper of the potentiometer is adjusted and the galvanometer briefly connected between the sliding contact and the unknown voltage. The deflection of the galvanometer is observed and the sliding tap adjusted until the galvanometer no longer deflects from zero. At that point the galvanometer draws no current from the unknown source, and the magnitude of voltage can be calculated from the position of the sliding contact. This null balance measuring method is still important in electrical metrology and standards work and is also used in other areas of electronics. Measurement potentiometers are"
"The thermo-galvanometer designed by Mr W. Duddell can be used for the measurement of extremely small currents to a high degree of accuracy. It has practically no self-induction or capacity and can therefore be used on a circuit of any frequency (even up to 120,000~ per sec.) and currents as small as twenty micro-amperes can be readily measured by it . It is equally correct on continuous and alternating currents. It can therefore be accurately standardized by continuous current and used without error on circuits of any frequency or wave-form. The principle of the thermo-galvanometer is simple. The instrument consists"
"cable during its manufacture and submersion. Moreover, it proved the best apparatus for receiving messages through a long cable. The following is adapted from a contemporary account of Thomson's instrument: Moving coil galvanometer was developed independently by Marcel Deprez and Jacques-Arsène d'Arsonval about 1880. Deprez's galvanometer was developed for high currents, while D'Arsonval designed his to measure weak currents. Unlike in the Kelvin's galvanometer, in this type of galvanometer the magnet is stationary and the coil is suspended in the magnet gap. The mirror attached to the coil frame rotates together with it. This form of instrument can be more"
"spring. The vibration galvanometer is used for detecting alternating currents in the frequency of its natural resonance. Most common application is as a null indicating instrument in AC bridge circuits and current comparators. The sharp resonance of the vibration galvanometer makes it very sensitive to changes in the measured current frequency and it can be used as an accurate tuning device. The frequency-sensitive behaviour of the galvanometer allows their use as a crude frequency meter, commonly used for adjusting the speed of AC generator sets. The galvanometer is constructed as a number of moving-iron galvanometers, sharing the same excitation coil."
"measured in Kpps (kilo points per second). Available speeds include 8k, 12k, 20k, 30k, 35k, 50k, and 60k. The faster the galvanometers, the smoother and more flicker-free the projected image. Each galvanometer moves the beam in one plane, either X axis or Y axis. Placing the galvanometers close together at 90 degrees to each other allows full movement of the laser beam within a defined square area. The most useful specifications of a galvanometer pair for laser show use are the speed at which they can draw points, and the angle at which they achieve this speed. Galvanometers come in"
"is almost universally used in moving-coil meters today. Initially laboratory instruments relying on the Earth's own magnetic field to provide restoring force for the pointer, galvanometers were developed into compact, rugged, sensitive portable instruments essential to the development of electro-technology. The taut-band movement is a modern development of the D'Arsonval-Weston movement. The jewel pivots and hairsprings are replaced by tiny strips of metal under tension. Such a meter is more rugged for field use. Some galvanometers use a solid pointer on a scale to show measurements; other very sensitive types use a miniature mirror and a beam of light to"
"is called the Reduction Factor of the tangent galvanometer. One problem with the tangent galvanometer is that its resolution degrades at both high currents and low currents. The maximum resolution is obtained when the value of is 45°. When the value of is close to 0° or 90°, a large percentage change in the current will only move the needle a few degrees. A tangent galvanometer can also be used to measure the magnitude of the horizontal component of the geomagnetic field. When used in this way, a low-voltage power source, such as a battery, is connected in series with"
"digital instrument are higher precision and accuracy, but factors such as power consumption or cost may still favour application of analog meter movements. Most modern uses for the galvanometer mechanism are in positioning and control systems. Galvanometer mechanisms are divided into moving magnet and moving coil galvanometers; in addition, they are divided into ""closed-loop"" and ""open-loop"" - or ""resonant"" - types. ""Mirror"" galvanometer systems are used as beam positioning or beam steering elements in laser scanning systems. For example, for material processing with high-power lasers, closed loop mirror galvanometer mechanisms are used with servo control systems. These are typically high"
"capacitance C, the voltage V and the deflection d: formula_1 where K is expressed in coulombs per centimeter. In operation the unknown quantity of charge Q (in coulombs) is simply: formula_2. An interesting form of ballistic galvanometer is the Grassot fluxmeter. In order to operate correctly, the discharge time through the regular ballistic galvanometer must be shorter than the period of oscillation. For some applications, especially those involving inductors, this condition cannot be met. The Grassot fluxmeter solves this. Its construction is similar to that of a ballistic galvanometer, but its coil is suspended without any restoring forces in the"
"a semiconductor surface or interface or graphene. When a voltmeter is used to measure an electronic device, it does not quite measure the pure electric potential (also called Galvani potential). Instead, it measures the electrochemical potential, also called ""fermi level difference"", which is the ""total"" free energy difference per electron, including not only its electric potential energy but also all other forces and influences on the electron (such as the kinetic energy in its wavefunction). For example, a p-n junction in equilibrium, there is a galvani potential (built-in potential) across the junction, but the ""voltage"" across it is zero (in"
"Salinometer A salinometer is a device designed to measure the salinity, or dissolved salt content, of a solution. Since the salinity affects both the electrical conductivity and the specific gravity of a solution, a salinometer often consist of an ec meter or hydrometer and some means of converting those readings to a salinity reading. A salinometer may be calibrated in either micromhos, a unit of electrical conductivity, (usually 0-22) or else directly calibrated for salt in 'grains per gallon' (0-0.5). A typical reading on-board ship would be 2 micromhos or 0.05 grains per gallon. A reading of twice this may"
"Vibration galvanometer A vibration galvanometer is a type of mirror galvanometer, usually with a coil suspended in the gap of a magnet or with a permanent magnet suspended in the field of an electromagnet. The natural oscillation frequency of the moving parts is carefully tuned to a specific frequency; commonly 50 or 60 Hz. Higher frequencies up to 1 kHz are possible. Since the frequency depends on the mass of the moving elements, high frequency vibration galvanometers are very small with light coils and mirrors. The tuning of the vibration galvanometer is done by adjusting the tension of the suspension"
"is noted that what one experimentally measures using an inert metallic probe and a voltmeter is formula_6. Galvani potential Galvani potential (also called Galvani potential difference, or inner potential difference, Δφ, delta phi) in electrochemistry, is the electric potential difference between two points in the bulk of two phases. These phases can be two different solids (e.g., two metals joined together), or a solid and a liquid (e.g., a metal electrode submerged in an electrolyte). Generally, the Galvani potential difference is measurable only when the two phases have identical chemical composition. The Galvani potential is named after Luigi Galvani. First,"
"galvanometer in the 19th century, or an electronically amplified instrument today . The ratio of resistances from one decade to the next is, surprisingly, not critical — by using ""R"" resistances slightly higher than ""R"" / 5 and connecting a trimming resistor in parallel to the entire preceding decade in order to trim the effective resistance down to 2 × ""R"". In the above example, the second stage might use 3 kΩ resistors instead of 2 kΩ; connecting a (trimmable) resistor of 60 kΩ in parallel with the second stage brings the total input resistance of the second stage down"
"from a mirrored scale is improved by positioning one's head while reading the scale so that the pointer and the reflection of the pointer are aligned; at this point, the operator's eye must be directly above the pointer and any parallax error has been minimized. Probably the largest use of galvanometers was of the D'Arsonval/Weston type used in analog meters in electronic equipment. Since the 1980s, galvanometer-type analog meter movements have been displaced by analog to digital converters (ADCs) for many uses. A digital panel meter (DPM) contains an analog to digital converter and numeric display. The advantages of a"
"reflectometers. Galvanometer mechanisms were also used to get readings from photoresistors in the metering mechanisms of film cameras (as seen in the adjacent image). In analog strip chart recorders such as used in electrocardiographs, electroencephalographs and polygraphs, galvanometer mechanisms were used to position the ""pen"". Strip chart recorders with galvanometer driven pens may have a full scale frequency response of 100 Hz and several centimeters of deflection. The deflection of a magnetic compass needle by current in a wire was first described by Hans Oersted in 1820. The phenomenon was studied both for its own sake and as a means"
"light enters through the slit to record on the film. Some photokymographs have a lens so an appropriate speed for the film can be reached. The galvanometer is an early instrument used to measure the strength of an electric current. Hermann von Helmholtz used it to detect the electrical signals generated by nerve impulses, and thus to measure the time taken by impulses to travel between two points on a nerve. This apparatus was designed to produce several fixed frequencies at different levels of intensity. It could either deliver the tone to a subject’s ear or transmit sound oscillations to"
"a variable volume container using a floating piston sampling device to minimize light end losses. A urinometer is a medical hydrometer designed for urinalysis. As urine's specific gravity is dictated by its ratio of solutes (wastes) to water, a urinometer makes it possible to quickly assess a patient's overall level of hydration. A barkometer is calibrated to test the strength of tanning liquors used in tanning leather. The state of charge of a lead-acid battery can be estimated from the density of the sulfuric acid solution used as electrolyte. A hydrometer calibrated to read specific gravity relative to water at"
"of his patents, filed in England, was a primary reference of Theodor Scheimpflug, who disclaimed inventing the falsely eponymous Scheimpflug principle. He died in 1921 in a car accident in Joigny, France. Jules Carpentier was one of the first manufacturers of various models of Galvanometer that had been designed by Marcel Deprez and Arsène d'Arsonval. In addition, Carpentier developed with other people like Eleuthère Mascart, Pellat, Broca, André Blondel, Abraham, Louis Le Chatelier and Callender a series of derivatives of Galvanometer to measure and record intensity, potential tensions and other amounts derived from them. The French engineer and inventor has"
"suspension thread or in the current leads. The core (bobbin) of the coil is of a non-conductive material. When an electric charge is connected to the instrument, the coil starts moving in the magnetic field of the galvanometer's magnet, generating an opposing electromotive force and coming to a stop regardless of the time of the current flow. The change in the coil position is proportional only to the quantity of charge. The coil is returned to the zero position manually or by reversing the direction of the current. Ballistic galvanometer A ballistic galvanometer is a type of sensitive galvanometer; commonly"
"for everything from laser etching hand tools, containers, and parts to batch-coding semiconductor wafers in semiconductor device fabrication. They typically control X and Y directions on and CO laser markers to control the position of the infrared power laser spot. Laser ablation, laser beam machining and wafer dicing are all industrial areas where high-speed mirror galvanometers can be found. This moving coil galvanometer is mainly used to measure very feeble or low currents of order 10 A. To linearise the magnetic field across the coil throughout the galvanometer's range of movement, the d'Arsonval design of a soft iron cylinder is"
"and voltage by using a Wheatstone bridge, and comparing the unknown quantity to a reference voltage or resistance. While useful in the lab, the devices were very slow and impractical in the field. These galvanometers were bulky and delicate. The D'Arsonval–Weston meter movement uses a moving coil which carries a pointer and rotates on pivots or a taut band ligament. The coil rotates in a permanent magnetic field and is restrained by fine spiral springs which also serve to carry current into the moving coil. It gives proportional measurement rather than just detection, and deflection is independent of the orientation"
"attached to the magnets. A beam of light reflected from the mirror fell on a graduated scale across the room, acting as a long mass-less pointer. 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. In a device called an oscillograph, the moving beam of light was used, to produce graphs of current versus time, by recording measurements on photographic film. The string galvanometer was a type of mirror galvanometer so sensitive that it was used"
"mainly used in some types of laser-based bar-code scanners, printing machines, imaging applications, military applications and space systems. Their non-lubricated bearings are especially of interest in applications that require functioning in a high vacuum. Moving coil type galvanometer mechanisms (called 'voice coils' by hard disk manufacturers) are used for controlling the ""head positioning"" servos in hard disk drives and CD/DVD players, in order to keep mass (and thus access times), as low as possible. A major early use for galvanometers was for finding faults in telecommunications cables. They were superseded in this application late in the 20th century by time-domain"