The Faraday cup electrometer is the simplest form of an electrical aerosol instrument used in aerosol studies. It consists of an electrometer and a filter inside a Faraday cage. Charged particles collected by the filter generate an electric current which is measured by the electrometer.
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The photosensitive surface was pulled slowly past of the aperture diaphragm of the camera box, which also housed an electrometer, and captured ongoing movements of the electrometer indices as a trace. Kelvin used similar photographic means for his quadrant electrometer (see above) in the 1860s.
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It was the forerunner of Kelvin's quadrant electrometer (described below).
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It is connected to the electrometer circuit which measures the current.
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Volta Electrometers Kolbe electrometer, precision form of gold-leaf instrument. This has a light pivoted aluminum vane hanging next to a vertical metal plate. When charged the vane is repelled by the plate and hangs at an angle. An electrometer is an electrical instrument for measuring electric charge or electrical potential difference.
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Early quadrant electrometer. While the term "quadrant electrometer" eventually referred to Kelvin's version, this term was first used to describe a simpler device. It consists of an upright stem of wood, to which is affixed to a semicircle of ivory. From the center there hangs a light cork ball upon a pivot.
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He published at Norwich in 1789 a quarto volume of Miscellaneous Experiments and Remarks on Electricity, the Air Pump, and the Barometer, with a description of an Electrometer of a new construction. The work was translated into German and published at Leipzig in 1790. A paper by him, Of a new Electrometer, appeared in the Philosophical Transactions (abridg. xv. 308), 1782.
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The potential measurements are performed with the positive terminal of the electrometer connected to the working electrode and the negative terminal to the reference electrode.
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One of Lippmann's early discoveries was the relationship between electrical and capillary phenomena which allowed him to develop a sensitive capillary electrometer, subsequently known as the Lippmann electrometer which was used in the first ECG machine. In a paper delivered to the Philosophical Society of Glasgow on 17 January 1883, John G. M'Kendrick described the apparatus as follows: :Lippmann's electrometer consists of a tube of ordinary glass, 1 metre long and 7 millimetres in diameter, open at both ends, and kept in the vertical position by a stout support. The lower end is drawn into a capillary point, until the diameter of the capillary is .005 of a millimetre.
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She used an innovative technique to investigate samples. Fifteen years earlier, her husband and his brother had developed a version of the electrometer, a sensitive device for measuring electric charge. Using her husband's electrometer, she discovered that uranium rays caused the air around a sample to conduct electricity. Using this technique, her first result was the finding that the activity of the uranium compounds depended only on the quantity of uranium present.
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The deflection is observed by a beam of light reflected from a small mirror attached to the sector, just as in a galvanometer. The engraving on the right shows a slightly different form of this electrometer, using four flat plates rather than closed segments. The plates can be connected externally in the conventional diagonal way (as shown), or in a different order for specific applications. A more sensitive form of quadrant electrometer was developed by Frederick Lindemann.
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High charging efficiency allows sufficient charge to be placed on individual particles that the use of electrometer detectors is practicable, while the use of parallel electrometer detectors allows real time measurement of the size/number spectrum with output data as fast as 0.25 Hz. Unlike SMPS-type devices, multiple charging is an inherent issue across almost the entire size range of EAS-type devices. Accurate characterization of the electrical charging of the aerosol is therefore an essential component of device design.
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A version of the above dosimeter without the self-reading capabilities, called a pocket ionization chamber or just pocket chamber, was widely used in World War II and postwar government and military projects, particularly the Manhattan project. This consisted of a simple ionization chamber with an electrode running down the center, but no electroscope for reading. Instead the exposure was read by plugging the device into a separate precision electrometer/charger, which measured the decline in charge on the electrode and displayed it on a meter, before recharging the electrode. These had the advantage that they were simpler, more rugged, and cheaper than the electrometer type, but the disadvantage (considered desirable in some military applications) that the exposure couldn't be read by the wearer without the electrometer/charger.
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A bias of 5mV is applied across the probe tips. The measured resistance can range from 1-ohm to one billion ohms. A "log R" amplifier or electrometer is used to measure the resistance.
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Electrostatic voltmeter operation Electrostatic voltmeter mechanism The operating principle of an electrostatic voltmeter is similar to that of an electrometer, it is, however, designed to measure high potential differences; typically from a few hundred to many thousands volts.
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Francis Rudolph Shonka (18 April 1906 – 11 October 1970) was a physicist and inventor. Shonka was known for his pioneering work with ionizing radiation measurement devices and equipment. This equipment bears his name today as the: Shonka ionization chamber, the Shonka electrometer, and Shonka plastics.
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The "amplifier" is actually an electrometer, sometimes referred to as a "unity gain amplifier"; its main purpose is to reduce the electrical load on the small signals (in the mV range) produced by cells so that they can be accurately recorded by low-impedance electronics. The amplifier increases the current behind the signal while decreasing the resistance over which that current passes. Consider this example based on Ohm's law: A voltage of 10 mV is generated by passing 10 nanoamperes of current across 1 MΩ of resistance. The electrometer changes this "high impedance signal" to a "low impedance signal" by using a voltage follower circuit.
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Minchin published the results of a few days' observations in the Proceedings of the Royal Society, describing the relative magnitudes of the stars Regulus, Arcturus and Procyon, and acknowledging Monck's measurements. It is believed he visited Wilson's home in 1894 and 1897, and he certainly did in September 1895 and January 1896, but no other observations were recorded. Minchin invented a metrological device, the absolute sine-electrometer, a very sensitive development of the gold-leaf electroscope; this device was further developed and marketed as a 'tilted gold-leaf electrometer' by the Cambridge Scientific Instrument Company, amongst others. He was elected a Fellow of the Royal Society in 1895.
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When gas between the electrodes is ionized by incident ionizing radiation, ion-pairs are created and the resultant positive ions and dissociated electrons move to the electrodes of the opposite polarity under the influence of the electric field. This generates an ionization current which is measured by an electrometer circuit. The electrometer must be capable of measuring the very small output current which is in the region of femtoamperes to picoamperes, depending on the chamber design, radiation dose and applied voltage. Each ion pair created deposits or removes a small electric charge to or from an electrode, such that the accumulated charge is proportional to the number of ion pairs created, and hence the radiation dose.
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In 1887 he used a capillary electrometer to record the first human electrocardiogram. He created the first practical ECG machine with surface electrodes. He lectured on it in Europe and America, often using his dog Jimmy in his ECG demonstrations. Initially Waller did not think electrocardiograms would be useful in hospitals.
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Hallwachs was a known as a builder of scientific instruments. Among the devices he invented are the electrometer quadrant and a double refractometer of great precision. Hallwachs was an assistant of Heinrich Hertz, in 1886, before the photoelectric effect was discovered. Hallwachs and Hertz, in 1887, carried on the investigations of electromagnetic waves.
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Most commonly used for radiation therapy measurements is a cylindrical or "thimble" chamber. The active volume is housed within a thimble shaped cavity with an inner conductive surface (cathode) and a central anode. A bias voltage applied across the cavity collects ions and produces a current which can be measured with an electrometer.
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His name is associated with the "Ebert-Fastie spectrometer", an optical device built by William George Fastie of Johns Hopkins University based on Ebert's design of a monochromator in 1889,UNIS Spec4XP The Ebert-Fastie Spectrometer Control Hardware and Software and "Ebert's apparatus", an electrometer used to measure the concentration of atmospheric ions.
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John G. M'Kendrick, "Note on a Simple Form of Lippmann's Capillary Electrometer useful to Physiologists".See also a similar description in German at "Kapillārelektromēter", Meyers Konversationslexikon, Verlag des Bibliographischen Instituts, Leipzig und Wien, 1885–1892. Retrieved 5 December 2010. Lippmann's PhD thesis, presented to the Sorbonne on 24 July 1875, was on electrocapillarity.
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CK5889 Electrometer pentode data sheet In a specialized circuit called inverted triode, the roles of anode and grid are reversed. This places the control electrode at a maximum distance from the space-charge region surrounding the filament, minimizing the amount of electrons collected by the control electrode, and thus minimizing the input current.
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Thomson did more than any other electrician up to his time in introducing accurate methods and apparatus for measuring electricity. As early as 1845 he pointed out that the experimental results of William Snow Harris were in accordance with the laws of Coulomb. In the Memoirs of the Roman Academy of Sciences for 1857 he published a description of his new divided ring electrometer, based on the old electroscope of Johann Gottlieb Friedrich von Bohnenberger and he introduced a chain or series of effective instruments, including the quadrant electrometer, which cover the entire field of electrostatic measurement. He invented the current balance, also known as the Kelvin balance or Ampere balance (SiC), for the precise specification of the ampere, the standard unit of electric current.
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Saussure (1779) recorded data relating to a conductor's induced charge in the atmosphere. Saussure's instrument (which contained two small spheres suspended in parallel with two thin wires) was a precursor to the electrometer. Saussure found that the atmospheric electrification under clear weather conditions had an annual variation, and that it also varied with height.
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Thomson could trace the path of the ray by observing the phosphorescent patch it created where it hit the surface of the tube. Thomson observed that the electrometer registered a charge only when he deflected the cathode ray to it with a magnet. He concluded that the negative charge and the rays were one and the same.
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Alexander McAdie repeated Benjamin Franklin's kite experiments with an electrometer. In 1887, Eddy heard of Woodbridge Davis' maneuverable kites. Based on accounts of tailless diamond kites common in Java, he tried to fill in the missing details. In standard diamond kites the tail was needed for stabilization, but was problematic when chaining several kites in order to reach higher altitudes.
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Bremer started his brain transection experiments at an opportune time. Neurophysiological techniques had greatly improved during the early 1930s with the introduction of Alex Forbes' electronic amplification. Electromagnetic oscillographs had replaced the Lippman electrometer and the string galvanometer in electrophysiological experiments. These newly introduced techniques allowed Lord Adrian and Matthews to confirm Hans Bergers revolutionary discovery of alpha electroencephalographic activity in humans.
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150 The lowercase symbol q is often used to denote a quantity of electricity or charge. The quantity of electric charge can be directly measured with an electrometer, or indirectly measured with a ballistic galvanometer. The amount of charge in 1 electron (elementary charge) is defined as a fundamental constant in the SI system of units, (effective from 20 May 2019)., p.
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George Minchin Minchin (born George Minchin Smith, 1845-1914) was an Irish mathematician and experimental physicist. He was a pioneer in the development of astronomical photometry: the first-ever celestial photometric measurements were made using photovoltaic cells that he developed for the purpose. He invented the absolute sine-electrometer and was a prolific author of mathematical and scientific textbooks and papers.
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Lord Kelvin's Quadrant Electrometer Developed by Lord Kelvin, this is the most sensitive and accurate of all the mechanical electrometers. The original design uses a light aluminum sector suspended inside a drum cut into four segments. The segments are insulated and connected diagonally in pairs. The charged aluminum sector is attracted to one pair of segments and repelled from the other.
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In Kelvin probe force microscopy, a conducting cantilever is scanned over a surface at a constant height in order to map the work function of the surface. A typical scanning Kelvin probe (SKP) instrument. On the left is the control unit with lock-in amplifier and backing potential controller. On the right is the x, y, z scanning axis with vibrator, electrometer and probe mounted.
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The action and efficiency of influence machines were further investigated by F. Rossetti, A. Righi, and Friedrich Kohlrausch. E. E. N. Mascart, A. Roiti, and E. Bouchotte also examined the efficiency and current producing power of influence machines. In 1871, sectorless machines were investigated by Musaeus. In 1872, Righi's electrometer was developed and was one of the first antecedents of the Van de Graaff generator.
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Pierre and Marie Curie in their laboratory Curie worked with his wife in isolating polonium and radium. They were the first to use the term "radioactivity", and were pioneers in its study. Their work, including Marie Curie's celebrated doctoral work, made use of a sensitive piezoelectric electrometer constructed by Pierre and his brother Jacques Curie. Pierre Curie's 1898 publication with his wife and M. G. BémontP.
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He inserted silver wires under the scalps of his patients. These were later replaced by silver foils attached to the patient's head by rubber bandages. Berger connected these sensors to a Lippmann capillary electrometer, with disappointing results. However, more sophisticated measuring devices, such as the Siemens double-coil recording galvanometer, which displayed electric voltages as small as one ten thousandth of a volt, led to success.
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Electrical aerosol spectrometry (EAS) is a technique for measurement of the number-size distribution of aerosol using a combination of electrical charging and multiple solid state electrometer detectors. The technique combines both diffusion and field charging regimes to cover the diameter range 10 nm to 10 μm. Subsequent developments of the technique enable measurements faster than 1 Hz, although in each case with a reduced size range.
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The Bohnenberger electrometer, developed by J. G. F. von Bohnenberger from an invention by T. G. B. Behrens, consists of a single gold leaf suspended vertically between the anode and cathode of a dry pile. Any charge imparted to the gold leaf causes it to move toward one or the other pole; thus, the sign of the charge as well as its approximate magnitude may be gauged.
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Commercially made Geiger counters are expensive and require frequent calibration. It is possible to construct an electrometer-type radiation meter called the Kearny fallout meter, which does not require batteries or professional calibration, from properly-scaled plans with just a coffee can or pail, gypsum board, monofilament fishing line, and aluminum foil. Plans are freely available in the public domain in the reference Nuclear War Survival Skills by Cresson Kearny.
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Bowler & Morus, pages 403–404 Cooke had some ideas for building a telegraph prior to his partnership with Wheatstone and had consulted scientist Michael Faraday for expert advice. In 1836, Cooke built both an experimental electrometer system and a mechanical telegraph involving a clockwork mechanism with an electromagnetic detent. However, much of the scientific knowledge for the model actually put into practice came from Wheatstone. Cooke's earlier ideas were largely abandoned.
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He also studied and described for the first time the nature of EEG alterations in brain diseases such as epilepsy. His method involved inserting silver wires under the patients scalp, one at the front of the head and one at the back. Later he used silver foil electrodes attached to the head by a rubber bandage. As a recording device he first used the Lippmann's capillary electrometer, but results were disappointing.
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Efforts to amplify biosignals started with the development of electrocardiography. In 1887, Augustus Waller, a British physiologist, successfully measured the electrocardiograph of his dog using two buckets of saline, in which he submerged each of the front and the hind paws.Webster, John G. (2006) Encyclopedia of Medical Devices and Instrumentation Volume I. New Jersey: Wiley-Interscience. . A few months later, Waller successfully recorded the first human electrocardiography using the capillary electrometer.
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The proton has a charge that is equal and opposite, and thus +1.6022×10−19 coulomb. Charge is possessed not just by matter, but also by antimatter, each antiparticle bearing an equal and opposite charge to its corresponding particle. Charge can be measured by a number of means, an early instrument being the gold-leaf electroscope, which although still in use for classroom demonstrations, has been superseded by the electronic electrometer.
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This principle has been used to detect ionizing radiation, as seen in the quartz fibre electrometer and Kearny fallout meter. This type of electroscope usually acts as an indicator and not a measuring device, although it can be calibrated. The Braun electroscope replaced the gold-leaf electroscope for more accurate measurements. The instrument was developed in the 18th century by several researchers, among them Abraham Bennet (1787) and Alessandro Volta.
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Nollet is reputed to be the first to apply the name "Leyden jar" to the first device for storing electricity. Nollet's invention was replaced by Horace-Bénédict de Saussure's electrometer in 1766. By the 1740s, William Watson had conducted several experiments to determine the speed of electricity. The general belief at the time was that electricity was faster than sound, but no accurate test had been devised to measure the velocity of a current.
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The outer layer of the flat panel in this design is typically a high-voltage bias electrode. X-ray photons create electron-hole pairs in a-Se, and the transit of these electrons and holes depends on the potential of the bias voltage charge. As the holes are replaced with electrons, the resultant charge pattern in the selenium layer is read out by a TFT array, active matrix array, electrometer probes or microplasma line addressing.
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This section hosts a number of instruments used by Volta's successors while occupying the Physics chair. There are more than 600 instruments, some of them are unique. Giuseppe Belli added many instruments to the collection, many were his own, including an electrostatic induction generator, a magneto-electric motor, a modified Bohnenberger electrometer and an electrostatic generator. This massive collection were further expanded by his successors, Giovanni Cantoni and others who followed after him.
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Pierre and Marie Skłodowska-Curie, 1895 In 1880, Pierre and his older brother Jacques (1856–1941) demonstrated that an electric potential was generated when crystals were compressed, i.e. piezoelectricity. To aid this work they invented the piezoelectric quartz electrometer. The following year they demonstrated the reverse effect: that crystals could be made to deform when subject to an electric field. Almost all digital electronic circuits now rely on this in the form of crystal oscillators.
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Schoelkopf's techniques emphasize high-speed, high-sensitivity measurements performed on nanostructures at low temperatures. Together with his former supervisor Daniel Prober and his laboratory team, Schoelkopf invented the Radio-Frequency Single-Electron Transistor, an electrometer capable of measuring sub-electron charges on nano-second timescales. This new transistor allowed them to study electrical transport at the single-charge level in various systems. They also developed new types of sensors and detectors that employ these capabilities.
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The galvanometer was made possible in 1820 by the discovery by Hans Christian Ørsted that electric currents would deflect a compass needle, and the gold- leaf electroscope was even earlier (Abraham Bennet, 1786).Keithley, p. 36 Yet Golding Bird could still write in 1848 that "the irritable muscles of a frog's legs were no less than 56,000 times more delicate a test of electricity than the most sensitive condensing electrometer."Bird, p.
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Also, he was the first scientist to solve the problem involving refraction of seismic rays in spherical layers. The term Benndorfscher Satz (Benndorf's relationship) is used to describe the constancy of the ray parameter across the spherical layers. METEOROLOGY AND GEOPHYSICS AND ITS AMBASSADORS AT THE UNIVERSITY OF GRAZ: A HISTORICAL SURVEY Bruno Besser A device known as a "Benndorf electrometer" is used for atmospheric electrical measurements. Physics of the air - William Jackson Humphries Physik.
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ECG as done by Willem Einthoven In the 19th century it became clear that the heart generated electric currents. The first to systematically approach the heart from an electrical point-of-view was Augustus Waller, working in St Mary's Hospital in Paddington, London. In 1911 he saw little clinical application for his work. The breakthrough came when Einthoven, working in Leiden, used his more sensitive string galvanometer, than the capillary electrometer that Waller used.
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An early ionometer is due to the Swiss physicist Heinrich Greinacher in 1913. However, Greinacher was not the first to build an ionometer, he credits one Bronson with building an instrument upon which Greinacher's was an improvement. Greinacher states the advantage of his instrument over Bronson's being in not requiring the quadrant electrometer (invented by Lord Kelvin).Greinacher, H, "The Ionometer and its Application to the Measurement of Radium and Röntgen Rays", Physikal. Zeitsch., vol 15, 1914, pp410-415.
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Devised in 1978 by Cresson Kearny, the Kearny fallout meter is an application of the gold-leaf electroscope developed in 1787 by Abraham Bennet. Prior to this, the use of the electrometer principle for radiation detection had seen widespread application in the form of the quartz fiber dosimeter. Professional radiation meters, while more accurate and more durable, had a number of potential issues, including cost and lack of availability, which it was hoped the Kearny fallout meter would address.
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Coulomb electrometer Torsion is used to give a measurement more sensitive than repulsion of gold leaves or cork-balls. It consists of a glass cylinder with a glass tube on top. In the axes of the tube is a glass thread, the lower end of this holds a bar of gum lac, with a gilt pith ball at each extremity. Through another aperture on the cylinder, another gum lac rod with gilt balls may be introduced.
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Together with Patrick d'Arcy, he constructed in 1749 the first electrometer, a device for detection of electrical charges and voltages. He also experimented with lightning conductors and with the use of electricity in the treatment of diseases. As contributor to the Encyclopédie, he wrote more than 130 articles under the author abbreviation "T", including those related to watchmaking, locksmith and mathematical instruments. From 1772 to 1777 Le Roy was deputy director and from 1773 to 1778, director of the Académie royale des sciences.
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Faraday used a gold-leaf electroscope, but modern demonstrations often use a modern electrometer because it is far more sensitive than an electroscope, can distinguish between positive and negative charge, and gives a quantitative readout., p.4-5 The container is discharged by connecting it briefly to a large conducting object, called a ground (earth); this can be done by touching it with a finger, using the conductive human body as a ground. Any initial charge drains off into the ground.
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Previous to the string galvanometer, scientists used a machine called the capillary electrometer to measure the heart's electrical activity, but this device was unable to produce results at a diagnostic level. Dutch physiologist Willem Einthoven developed the string galvanometer in the early 20th century, publishing the first registration of its use to record an electrocardiogram in a Festschrift book in 1902. The first human electrocardiogram was recorded in 1887, however only in 1901 was a quantifiable result obtained from the string galvanometer.
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Pierre Curie, known for his work on radioactivity as well as on ferromagnetism, paramagnetism, and diamagnetism; notably Curie's law and Curie point. Pierre and Marie further explored radioactivity by working to separate the substances in uranium ores and then using the electrometer to make radiation measurements to ‘trace’ the minute amount of unknown radioactive element among the fractions that resulted. Working with the mineral pitchblende, the pair discovered a new radioactive element in 1898. They named the element polonium, after Marie's native country of Poland.
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It is intended for service as a power amplifier driver where the potentials are obtained directly from a 12V automobile battery." The space-charge grid was operated at +12V, the same as the anode supply voltage. Another important application of the space-charge tetrode was as an electrometer tube for detecting and measuring extremely small currents. For example, the General Electric FP54 was described as a "space-charge grid tube ... designed to have a very high input impedance and a very low grid current.
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Their separation is a direct indication of the net charge stored on them. On the glass opposite the leaves, pieces of tin foil may be pasted, so that when the leaves diverge fully they may discharge into the ground. The leaves may be enclosed in a glass envelope to protect them from drafts, and the envelope may be evacuated to minimize charge leakage. A further cause of charge leakage is ionizing radiation, so to prevent this, the electrometer must be surrounded by lead shielding.
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Valve electrometers use a specialized vacuum tube (thermionic valve) with a very high gain (transconductance) and input resistance. The input current is allowed to flow into the high impedance grid, and the voltage so generated is vastly amplified in the anode (plate) circuit. Valves designed for electrometer use have leakage currents as low as a few femtoamperes (10−15 amperes). Such valves must be handled with gloved hands as the salts left on the glass envelope can provide leakage paths for these tiny currents.
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In contrast with the charge state of an atomic or molecular ion, the charge states of such an "island" involve a macroscopic number of conduction electrons of the island. The quantum superposition of charge states can be achieved by tuning the gate voltage U that controls the chemical potential of the island. The charge qubit is typically read-out by electrostatically coupling the island to an extremely sensitive electrometer such as the radio- frequency single-electron transistor. Typical T2 coherence times for a charge qubit are on the order of 1–2 μs.
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Henri Becquerel himself proved that beta rays are fast electrons, while Rutherford and Thomas Royds proved in 1909 that alpha particles are ionized helium. Rutherford and Edward Andrade proved in 1914 that gamma rays are like X-rays, but with shorter wavelengths. Cosmic ray radiations striking the Earth from outer space were finally definitively recognized and proven to exist in 1912, as the scientist Victor Hess carried an electrometer to various altitudes in a free balloon flight. The nature of these radiations was only gradually understood in later years.
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According to Gauss' law, the charge collected on the Faraday cup is the induced charge, that means that the filter does not need to be a conductor. It is typically used to measure particles of unipolar charge, which are particles with a net charge concentration that equals the charge concentration of positively or negatively charged particles. With an aerosol electrometer the transportation of charge by electrical charged aerosol particles can be measured as electric current. In a metal housing (Faraday cup) a particle filter is mounted on an insulator.
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Curie's systematic studies included two uranium minerals, pitchblende and torbernite (also known as chalcolite). Her electrometer showed that pitchblende was four times as active as uranium itself, and chalcolite twice as active. She concluded that, if her earlier results relating the quantity of uranium to its activity were correct, then these two minerals must contain small quantities of another substance that was far more active than uranium. She began a systematic search for additional substances that emit radiation, and by 1898 she discovered that the element thorium was also radioactive.
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An electroscope can only give a rough indication of the quantity of charge; an instrument that measures electric charge quantitatively is called an electrometer. The electroscope was the first electrical measuring instrument. The first electroscope was a pivoted needle (called the versorium), invented by British physician William Gilbert around 1600. a translation by P. Fleury Mottelay of William Gilbert (1600) Die Magnete, London The pith-ball electroscope and the gold-leaf electroscope are two classical types of electroscope that are still used in physics education to demonstrate the principles of electrostatics.
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These posited differences in energy were in fact later identified through the work of Max Planck and Albert Einstein. Keen to test his new cells, in late 1891 Minchin contacted a friend — William Monck – who had built an observatory with a 7.5 inch (19 cm) refractor at his home in Earlsfort Terrace, Dublin. For the experiment, Monck ordered a new quadrant electrometer after FitzGerald was unable to provide a suitable one. The following August, Minchin provided Monck with improved cells but returned to England because of bad weather.
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Francis Ronalds began observing the potential gradient and air-earth currents around 1810, including making continuous automated recordings. He resumed his research in the 1840s as the inaugural Honorary Director of the Kew Observatory, where the first extended and comprehensive dataset of electrical and associated meteorological parameters was created. He also supplied his equipment to other facilities around the world with the goal of delineating atmospheric electricity on a global scale. Kelvin's new water dropper collector and divided-ring electrometer were introduced at Kew Observatory in the 1860s, and atmospheric electricity remained a speciality of the observatory until its closure.
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The cathode ray tube by which J. J. Thomson demonstrated that cathode rays could be deflected by a magnetic field, and that their negative charge was not a separate phenomenon. While supporters of the aetherial theory accepted the possibility that negatively charged particles are produced in Crookes tubes, they believed that they are a mere by-product and that the cathode rays themselves are immaterial. Thomson set out to investigate whether or not he could actually separate the charge from the rays. Thomson constructed a Crookes tube with an electrometer set to one side, out of the direct path of the cathode rays.
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A regulated electron current (typically 10 mA) is emitted from a heated filament. The electrons are attracted to the helical grid by a DC potential of about +150 V. Most of the electrons pass through the grid and collide with gas molecules in the enclosed volume, causing a fraction of them to be ionized. The gas ions formed by the electron collisions are attracted to the central ion collector wire by the negative voltage on the collector (typically −30 V). Ion currents are on the order of 1 mA/Pa. This current is amplified and displayed by a high-gain differential amplifier/electrometer.
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The name 'voltameter' was coined by Daniell, who shortened Faraday's original name of "volta-electrometer".Frank A. J. L. James, (1991), The correspondence of Michael Faraday, IET, , letter 872, 9/1/1836 Hofmann voltameters are no longer used as electrical measuring devices. However, before the invention of the ammeter, voltameters were often used to measure direct current, since current through a voltameter with iron or copper electrodes electroplates the cathode with an amount of metal from the anode directly proportional to the total coulombs of charge transferred (Faraday's law of electrolysis). The modern name is "electrochemical coulometer".
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Just before leaving the role of preparer, Bourbouze noticed a young student, Pierre Curie who was preparing his Bachelor of Science degree in the Faculty of Science.Marie Curie et les conquérants de l'atome : 1896-2006, par Jean-Pierre Poirier He then took him as assistant to the preparation of François Leroux's physics course at the Ecole Supérieure de Pharmacie de Paris. Bourbouze also met Jacques Curie who succeeded him at the Ecole Supérieure de Pharmacie de Paris. In 1886, Bourbouze was the builder of an electrometer and an apparatus for the study of the piezoelectric quartz invited by the Curie brothers.
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The barometer > measures the weight (baro, weight) of the atmosphere; the electrometer > measures electric conditions; the psychometer measures the soul (psyche). In > the case of Psychometry, however, the measuring assumes a new character, as > the object measured and the measuring instrument are the same psychic > element, and its measuring power is not limited to the psychic as it was > developed in the first experiments, but has appeared by successive > investigation to manifest a wider and wider area of power, until it became > apparent that this psychic capacity was really the measure of all things in > the Universe.
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Vibrating reed electrometers use a variable capacitor formed between a moving electrode (in the form of a vibrating reed) and a fixed input electrode. As the distance between the two electrodes varies, the capacitance also varies and electric charge is forced in and out of the capacitor. The alternating current signal produced by the flow of this charge is amplified and used as an analogue for the DC voltage applied to the capacitor. The DC input resistance of the electrometer is determined solely by the leakage resistance of the capacitor, and is typically extremely high, (although its AC input impedance is lower).
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Since biological tissues have extremely low levels of electrical activity (in the range of microvolts), neurophysiology's progress had to wait for them. Like many German physiologists of his time, Marxow had a good knowledge and ability with physics, and invented a number of devices for the purpose of his studies, particularly the reonome (a kind of rheostat, or variable resistor used to control finely the intensity of an electrical stimulus). He also adapted the Lippmann's capillary electrometer in order to use it for measuring subtle bioelectrical phenomena. From the bioelectricity of nerves, Marxow turned his attention, from 1876 on, to the global electrical activity of the cerebral hemispheres.
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Quartz fiber radiation dosimeter, showing clip for securing it to clothing; normally a breast pocket. roentgen. Viewing is by holding the instrument towards an external light source and looking through the magnifying eyepiece. A quartz fiber dosimeter, sometimes called a self indicating pocket dosimeter (SIPD) or self reading pocket dosimeter (SRPD) or quartz fibre electrometer (QFE), is a type of radiation dosimeter, a pen-like device that measures the cumulative dose of ionizing radiation received by the device, usually over one work period. It is clipped to a person's clothing, normally a breast pocket for whole body exposure, to measure the user's exposure to radiation.
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Born in Bologna, Righi was educated in his home town, taught physics at Bologna Technical College between 1873 and 1880, and left to take up the newly established chair of physics at the University of Palermo. He was professor of physics at the University of Padua (1885–89) and later returned to a professorship at the University of Bologna. Righi's early research, conducted in Bologna between 1872 and 1880, was primarily in electrostatics. He invented an induction electrometer, with the help of Dr. Matthew Van Schaeick of the Humboldt University of Berlin, in 1872, capable of detecting and amplifying small electrostatic charges, formulated mathematical descriptions of vibrational motion, and discovered magnetic hysteresis in 1880.
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Continuing earlier studies of Keith Lucas, he used a capillary electrometer and cathode ray tube to amplify the signals produced by the nervous system and was able to record the electrical discharge of single nerve fibres under physical stimulus. (It seems he used frogs in his experiments) An accidental discovery by Adrian in 1928 proved the presence of electricity within nerve cells. Adrian said, > I had arranged electrodes on the optic nerve of a toad in connection with > some experiments on the retina. The room was nearly dark and I was puzzled > to hear repeated noises in the loudspeaker attached to the amplifier, noises > indicating that a great deal of impulse activity was going on.
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A modern electrometer is a highly sensitive electronic voltmeter whose input impedance is so high that the current flowing into it can be considered, for most practical purposes, to be zero. The actual value of input resistance for modern electronic electrometers is around 1014Ω, compared to around 1010Ω for nanovoltmeters.Keithley, Making precision low current and high resistance measurements, "A greater measure of confidence" brochure, 2011, page 8 Owing to the extremely high input impedance, special design considerations must be applied to avoid leakage current such as driven shields and special insulation materials. Among other applications, electrometers are used in nuclear physics experiments as they are able to measure the tiny charges left in matter by the passage of ionizing radiation.
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In 1909, Theodor Wulf developed an electrometer, a device to measure the rate of ion production inside a hermetically sealed container, and used it to show higher levels of radiation at the top of the Eiffel Tower than at its base. However, his paper published in Physikalische Zeitschrift was not widely accepted. In 1911, Domenico Pacini observed simultaneous variations of the rate of ionization over a lake, over the sea, and at a depth of 3 metres from the surface. Pacini concluded from the decrease of radioactivity underwater that a certain part of the ionization must be due to sources other than the radioactivity of the Earth. :Translated and commented in 160px In 1912, Victor Hess carried three enhanced-accuracy Wulf electrometers to an altitude of 5,300 metres in a free balloon flight.
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Even Johnson recognized the potential for exploration, stating, "How easily shall we trace the Nile through all its passages; pass over to distant regions and examine the face of nature, from one extremity of the Earth to the other." Blanchard's companion Dr. John Jeffries considered ballooning to be a major part of an exploration of the secrets of flight, the nature of the upper atmosphere, and the formation of weather, and took instruments such as a mercury barometer, a thermometer, a hydrometer and an electrometer to take different measurements of the upper atmosphere. There were other positive scientific responses, as well. Upon receiving a letter from a friend chronicling a balloon flight, the astronomer William Herschel began to think of balloons as possibly useful for observation, as they might carry telescopes into the upper air, where it was clearer.
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Schema of Einthoven galvanometer, with quartz filament marked a-a'- 1903 Previous to the string galvanometer, scientists were using a machine called the capillary electrometer to measure the heart’s electrical activity, but this device was unable to produce results of a diagnostic level.'Einthoven's String GalvanometerThe First Electrocardiograph', Moises Rivera-Ruiz et al, Tex Heart Inst J. © 2008 by the Texas Heart Institute Willem Einthoven adapted the string galvanometer at Leiden University in the early 20th century, publishing the first registration of its use to record an electrocardiogram in a Festschrift book in 1902. The first human electrocardiogram was recorded in 1887; however, it was not until 1901 that a quantifiable result was obtained from the string galvanometer. In 1908, the physicians Arthur MacNalty, M.D. Oxon, and Thomas Lewis teamed to become the first of their profession to apply electrocardiography in medical diagnosis.
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RSM No.2 The Radiac Survey Meter No 2 or RSM was a 1955-meter which used an ionisation chamber to measure gamma radiation, it could measure beta, by removing the base-plate and opening the beta shield. This meter suffered from a number of disadvantages: it required three different types of batteries, of which two were obsolete and had to be manufactured to special order, the circuit included a single electrometer valve or tube. These were favored as they had been tested on fallout in Australia after the Operation Buffalo nuclear tests, and remained in use until 1982 by commissioning a manufacturer to regularly produce special production runs of the obsolete batteries. Within the ROC the RSM was only used at post sites for three years when it was superseded in 1958 by the FSM and the RSM retained only for post attack mobile monitoring missions. The ‘ROC Fixed Survey Meter’.
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