Also known as "attracted disk electrometers", attraction electrometers are sensitive balances measuring the attraction between charged disks. William Snow Harris is credited with the invention of this instrument, which was further improved by Lord Kelvin.
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The most common use for modern electrometers is the measurement of radiation with ionization chambers, in instruments such as geiger counters.
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Abraham Brook (fl. 1789) was an English bookseller in Norwich, now remembered as an experimental physicist, working with electrometers and vacuum flasks.
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Keithley Instruments' major product lines included testing and measurement products such as electrometers, voltmeters, signal generators, data acquisition, and production and benchtop parametric testers and analyzers.
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Everyday current meters for use in the field are called ammeters.Hackmann, p. 259 A similar distinction can be made between electroscopes, electrometers, and voltmeters for voltage measurements.
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Electrometers designed for use with ionization chambers may include a high-voltage power supply, which is used to bias the ionization chamber. Solid-state electrometers are often multipurpose devices that can measure voltage, charge, resistance and current. They measure voltage by means of "voltage balancing", in which the input voltage is compared with an internal reference voltage source using an electronic circuit with a very high input impedance (of the order of 1014 ohms). A similar circuit modified to act as a current-to-voltage converter enables the instrument to measure currents as small as a few femtoamperes.
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In subsequent work on magnetism Pierre Curie defined the Curie scale. This work also involved delicate equipment - balances, electrometers, etc. Nobel Lectures, Physics 1901-1921, Elsevier Publishing Company, Amsterdam, 1967. Pierre Curie was introduced to Maria Skłodowska by their friend, physicist Józef Wierusz-Kowalski.
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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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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 this scenario, the SET has appeared as a suitable candidate to achieve this low power range with high level of device integration. Applicable areas are among others: super-sensitive electrometers, single-electron spectroscopy, DC current standards, temperature standards, detection of infrared radiation, voltage state logics, charge state logics, programmable single-electron transistor logic.
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Quartz fiber can also be used for physical devices (such as in quartz fiber dosimeters and quartz fiber electrometers). Quartz fibers can be used in fiber optics. This is due to a quartz fiber having the ability to transport data at a speed of 1 terabit per second, and having a transmission loss of 1 decibel per kilometer.
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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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There are many different types, ranging from historical handmade mechanical instruments to high-precision electronic devices. Modern electrometers based on vacuum tube or solid-state technology can be used to make voltage and charge measurements with very low leakage currents, down to 1 femtoampere. A simpler but related instrument, the electroscope, works on similar principles but only indicates the relative magnitudes of voltages or charges.
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The output of the sensor is characteristic of the ion mobility distribution and can be used for detection and identification purposes. Principle of operation of a differential mobility analyzer for aerosol separation A DMA can separate charged aerosol particles or ions according to their mobility in an electric field prior to their detection, which can be done with several means, including electrometers or the more sophisticated mass spectrometers.
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In his Nobel Prize lecture, Bothe described how he had implemented the coincidence method in an experiment on Compton scattering in 1924. The experiment aimed to check whether Compton scattering produces a recoil electron simultaneously with the scattered gamma ray. Bothe used two point discharge counters connected to separate fibre electrometers and recorded the fibre deflections on a moving photographic film. On the film record he could discern coincident discharges with a time resolution of approximately 1 millisecond.
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It employs a metal-coated quartz fiber instead of an aluminum sector. The deflection is measured by observing the movement of the fiber under a microscope. Initially used for measuring star light, it was employed for the infrared detection of airplanes in the early stages of World War II. Some mechanic electrometers were housed inside a cage often referred to as a “bird cage”. This is a form of Faraday Cage that protected the instrument from external electrostatic charges.
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The exhibit is divided into the following thematic collections — electrical, optics, pneumatics, thermology, mechanics and geodesy. Some of these instruments include solar microscope, a Silbermann device, a Foucault pendulum, a Thomson ammeter, a Regnault hypsometer as well an Atwood machine, various coils, resistors, capacitors, electromagnets, electrometers, spectrometers, photometers, sextants, theodolites and rings. This section also includes a hyperbaric chamber designed and used by Carlo Forlanini between 1901 and 1918 for inducing artificial pneumothorax — which was the first successful cure for tuberculosis.
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Nollet's theory at first gained wide acceptance, but met resistance in 1752 with the translation of Franklin's Experiments and Observations on Electricity into French. Franklin and Nollet debated the nature of electricity, with Franklin supporting action at a distance and two qualitatively opposing types of electricity, and Nollet advocating mechanical action and a single type of electrical fluid. Franklin's argument eventually won and Nollet's theory was abandoned. In 1748, Nollet invented one of the first electrometers, the electroscope, which showed electric charge using electrostatic attraction and repulsion.
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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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The most modern electrometers consist of a solid state amplifier using one or more field-effect transistors, connections for external measurement devices, and usually a display and/or data-logging connections. The amplifier amplifies small currents so that they are more easily measured. The external connections are usually of a co-axial or tri-axial design, and allow attachment of diodes or ionization chambers for ionising radiation measurement. The display or data-logging connections allow the user to see the data or record it for later analysis.
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In 1767, he completed his first tour of Mont-Blanc, a trip that did much to reveal the topography of the snowy portions of the Alps of Savoy. He also carried out experiments on heat and cold, on the weight of the atmosphere and on electricity and magnetism. For this, he devised what became one of the first electrometers. Other trips led him to Italy, where he studied Mt. Etna and other volcanoes (1772–73),Daniela Vaj, "Saussure à la découverte de l'Italie (1772–1773)", in René Sigrist (ed.), H.-B.
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An incredibly extensive array of precise instrumentation had to be readily available for Humboldt's terrestrial physicist. The expansive amount of scientific resources that characterized the Humboldtian scientist is best described in the book Science in Culture, > Thus the complete Humboldtian traveller, in order to make satisfactory > observations, should be able to cope with everything from the revolution of > the satellites of Jupiter to the carelessness of clumsy donkeys.Cannon, > Science in Culture, p. 76 Just some of such instruments included chronometers, telescopes, sextants, microscopes, magnetic compasses, thermometers, hygrometers, barometers, electrometers, and eudiometers.
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Ronalds also established a sophisticated atmospheric electricity observing system at Kew with a long copper rod protruding through the dome of the observatory and a suite of novel electrometers and electrographs to manually record the data. He supplied this equipment to facilities in England, Spain, France, Italy, India (Colaba and Trivandrum) and the Arctic with the goal of delineating atmospheric electricity on a global scale. At Kew, two-hourly data was recorded in the Reports of the British Association between 1844 and 1847. An entirely new system, providing continuous automatic recording, was installed by Lord Kelvin personally in the early 1860s.
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The pendulum rod was of deal wood and terminated in a loaded bulb of brass and lead of 2 lbs in weight with a steel point which acted upon a smooth surface of hard baked chalk. When the top of the building was distributed by the shock of an earthquake, the steel point would inscribe a result in the chalk. At the top of the house, he installed Electrometers with lighting wires conducted from trees around the building. These were fed to two gilded balls and cylinders for determining the negative and positive character of the electricity and the relative amount.
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A quality general-purpose electronics DMM is generally considered adequate for measurements at signal levels greater than 1 mV or 1 μA, or below about 100 MΩ; these values are far from the theoretical limits of sensitivity, and are of considerable interest in some circuit design situations. Other instruments—essentially similar, but with higher sensitivity—are used for accurate measurements of very small or very large quantities. These include nanovoltmeters, electrometers (for very low currents, and voltages with very high source resistance, such as 1 TΩ) and picoammeters. Accessories for more typical multimeters permit some of these measurements, as well.
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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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Finally the machine was installed in December 1784 and he received the sum of 3000 guilders for it. Sometime between 1793 and 1796 he returned to England, living in Poland Street in London (contrary to his brother Jonathan who remained in Rotterdam), probably due to the political unrest in the Dutch Republic. Here he continued his business and produced a number of smaller (simplified) electrostatic generators – a design that would be produced until the 1920s.D. J. Bryden, The British Journal for the History of Science (1977), 10 : pp 77-77 He also worked on electrometers, for which he invented a new design, air pumps and wrote scientific papers.
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The section hosts a number of collections of instruments used by Alessandro Volta during his tenure in the University of Pavia. Two work tables, which he used, host numerous instruments he used to investigate the properties of an electrical charge — electrophores, gold-leaf electroscope, condensing electroscope, electrometers, conductors and capacitors in various sizes and shapes. The collection also includes several Leyden jars, Nairne's electrostatic generator, eudiometers, Volta's pistol and a device to study gas expansions. At the centre of the room, there's a display of mechanical and pneumatic instruments which belonged to Ugo Foscolo high school in Pavia — instruments for studying motion on an inclined plane and elastic shocks, pulleys, pumps, fountain and a device for the study of air resistance.
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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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Kelvin Hughes Type 14/9 Radar from front Kelvin Hughes Type 14/9 Radar from side The Kelvin connection is based upon the professional relationship between William Thomson (later-Lord Kelvin) (1824–1907), Professor of Natural Philosophy at Glasgow University from 1846–1899 and James White (1824–1884), a Glasgow-based Optical Instrument Maker. White's association with Thomson lasted until he died, but without any legal deeds of co-partnership White bore the financial risks of their working partnership. James White founded the firm of James White, Optician and Philosophical Instrument Makers in Glasgow in 1850 and was involved in the supply and maintenance of apparatus for Thomson's university laboratory and worked with him on experimental constructions. By 1854, White was producing electrical instruments such as electrometers and electrical balances from Thomson's designs. William Thomson was appointed a director of the Atlantic Telegraph Company in 1856 and in 1858 was 'electrician' on HMS Agamemnon that laid the first transatlantic telegraph cable.
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A profound friendship was built up between Ouang and Langevin beyond their student-teacher relationship. During the World War II, while Langevin was under home arrest, Wang refused to work for ESPCI led by a pro-German director Jean Thibaud and joined Irène and Frédéric Joliot-Curie - also student of Paul Langevin - at their Institute du Radium, where he researched more in radioactivity until the liberation of Paris by allied forces and the return of Langevin to ESPCI. From that point to the middle of 1950s, while continuing the research in ionized gases based on Langevin's theory and his previous work, Wang made breakthroughs in the following domains: # Inventing high sensibility electrometers; # Measuring the absorption, dispersion and speed of ultrasound in fluid; # Proving the existence of negative electrophoresis discovered by Felix Ehrenhaft; # Using β ray to measure and control the thickness of emulsion on photo film and paper. Wang, Joliot-Curie and Biquard families in summer 1941 After the war, Wang was awarded with the Prix Hughes by the Academie des Sciences in 1945 for his contribution in the field of ionized gases; and was promoted by Centre national de la recherche scientifique (CNRS) from researcher to research director.
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