WorldWideScience

Sample records for ammeters

  1. Fission cross section for 242Am.met

    International Nuclear Information System (INIS)

    The neutron-induced fission cross section for 242Am.met (152y) was measured at the Livermore 100-MeV electron linac in the neutron energy range of 0.01 eV to 20 MeV. Fission fragments were detected using a hemispherical fission chamber. The neutron flux was measured below 10 keV using lithium glass scintillators. Above 10 keV, the 242Am.met fission cross section was measured relative to the 235U fission cross section. Below 20 eV, the data were fit with a sum of single-level Breit-Wigner resonances. Results for the distribution of fission widths, the average fission width, and the average level spacing are presented. The fission cross section in the 100 keV to 20 MeV range is compared with previous measurements

  2. 47 CFR 73.57 - Remote reading antenna and common point ammeters.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Remote reading antenna and common point... RADIO SERVICES RADIO BROADCAST SERVICES AM Broadcast Stations § 73.57 Remote reading antenna and common point ammeters. Remote reading antenna and common point ammeters may be used without further...

  3. The Moving-Coil Ammeter: Technical Terminology Bulletin. Terminotech, Vol. 2, No. 8.

    Science.gov (United States)

    General Electric Co. of Canada, Ltd., Montreal, Quebec.

    This issue of a bulletin of technological terminology is devoted to the moving-coil ammeter. A brief narrative on the subject is presented in both French and English. A English-French dictionary of terms comprises the bulk of the document. Explanatory illustrations are appended. (JB)

  4. Measuring Earth's Magnetic Field Simply.

    Science.gov (United States)

    Stewart, Gay B.

    2000-01-01

    Describes a method for measuring the earth's magnetic field using an empty toilet paper tube, copper wire, clear tape, a battery, a linear variable resistor, a small compass, cardboard, a protractor, and an ammeter. (WRM)

  5. 18 CFR 367.3950 - Account 395, Laboratory equipment.

    Science.gov (United States)

    2010-04-01

    .... (4) Calorimeters-bomb, flow, recording types, and other similar items. (5) Current batteries. (6...) Portable graphic ammeters, voltmeters, and wattmeters. (27) Portable loading devices. (28) Potential.... (39) Testing panels. (40) Testing resistors. (41) Thermometers—indicating and recording....

  6. Control of the Superconducting Magnets current Power Supplies of the TJ-II Gyrotrons; Control de las Fuentes de Corriente de las Bobinas Superconductoras de los Girotrones del TJ-II

    Energy Technology Data Exchange (ETDEWEB)

    Ros, A.; Fernandez, A.; Tolkachev, A.; Catalan, G.

    2006-07-01

    The TJ-II ECRH heating system consists of two gyrotrons, which can deliver a maximum power of 300 kW at a frequency of 53.2 GHz. Another 28 GHz gyrotron is going to be used in the Bernstein waves heating system. In order to get the required frequency, the gyrotrons need and homogeneous magnetic field of several tesla, which is generated by a superconducting coil field by a current source. This document describes the current source control as well as the high precision ammeters control. These ammeters measure the current in the superconducting coils. The user interface and the programming of the control system are described. The communication between devices is also explained. (author) 9 Refs.

  7. Control of the Superconducting Magnets current Power Supplies of the TJ-II Gyrotrons

    International Nuclear Information System (INIS)

    The TJ-II ECRH heating system consists of two gyrotrons, which can deliver a maximum power of 300 kW at a frequency of 53.2 GHz. Another 28 GHz gyrotron is going to be used in the Bernstein waves heating system. In order to get the required frequency, the gyrotrons need and homogeneous magnetic field of several tesla, which is generated by a superconducting coil field by a current source. This document describes the current source control as well as the high precision ammeters control. These ammeters measure the current in the superconducting coils. The user interface and the programming of the control system are described. The communication between devices is also explained. (author) 9 Refs

  8. Introduction to electronics

    CERN Document Server

    Korneff, Theodore

    1966-01-01

    Introduction to Electronics focuses on the study of electronics and electronic devices. Composed of 14 chapters, the book starts with discussions on dc circuits, including resistance, voltmeter, ammeter, galvanometer, internal resistance, and positive and negative currents. This topic is followed by discussions on ac circuits, particularly addressing voltage and current, average power, resistive load, complex plane, and parallel circuits. Discussions also focus on filters and tuned circuits, diodes, and power supplies. Particularly given attention are the processes, diagrams, and analyses

  9. Superconducting bolometer array with SQUID readout for submillimetre wavelength detection

    Energy Technology Data Exchange (ETDEWEB)

    May, T [Ruhr-Universitaet Bochum, Astronomisches Institut, Universitaetsstr. 150, D-44780 Bochum (Germany); Zakosarenko, V [Institute for Physical High Technology (IPHT), Winzerlaer Str. 10, D-07752 Jena (Germany); Boucher, R [Institute for Physical High Technology (IPHT), Winzerlaer Str. 10, D-07752 Jena (Germany); Kreysa, E [Max-Planck Institute for Radioastronomy, Bonn (Germany); Meyer, H-G [Institute for Physical High Technology (IPHT), Winzerlaer Str. 10, D-07752 Jena (Germany)

    2003-12-01

    We have tested a fully microfabricated superconducting bolometer array for astrophysical observations at submillimetre wavelengths. The system is cooled by a {sup 3}He sorption refrigerator operating in a pumped {sup 4}He cryostat. The transition edge bolometer uses a bilayer of molybdenum and a gold-palladium alloy with a transition temperature of around 500 mK as the thermometer. The bolometer is voltage biased, and the current is measured by a superconducting quantum interference device (SQUID) ammeter.

  10. Energy balance in motor vehicles

    Science.gov (United States)

    Dziubńiski, M.; Drozd, A.; Adamiec, M.; Siemionek, E.

    2016-09-01

    This paper present the concept of testing energy balance. The test was conducted on the test bench equipped with the alternator, battery and standard mounted current receivers. The course of measurements consisted in recording the indications of three ammeters and a tachometer. On the basis of the recorded current values, it was possible to determine: energy received from the battery, consumed by the receivers and the energy drawn from the alternator.

  11. 47 CFR 73.9009 - Manufacture for exportation.

    Science.gov (United States)

    2010-10-01

    ..., transfer 73.3578 Matter of right 73.3522 Procedures 73.3513 Ammeters, antenna and common point, Remote... Allotments, Table of (FM) 73.202 AM antenna systems 73.45 AM broadcast channels, Classes of 73.21, 73.23, 73.25, 73.26, 73.27, 73.29 AM definitions 73.14 AM directional antenna field measurements 73.61...

  12. 47 CFR Alphabetical Index - Part 73

    Science.gov (United States)

    2010-10-01

    ..., transfer 73.3578 Matter of right 73.3522 Procedures 73.3513 Ammeters, antenna and common point, Remote... Allotments, Table of (FM) 73.202 AM antenna systems 73.45 AM broadcast channels, Classes of 73.21, 73.23, 73.25, 73.26, 73.27, 73.29 AM definitions 73.14 AM directional antenna field measurements 73.61...

  13. Superconducting bolometer array with SQUID readout for submillimetre wavelength detection

    International Nuclear Information System (INIS)

    We have tested a fully microfabricated superconducting bolometer array for astrophysical observations at submillimetre wavelengths. The system is cooled by a 3He sorption refrigerator operating in a pumped 4He cryostat. The transition edge bolometer uses a bilayer of molybdenum and a gold-palladium alloy with a transition temperature of around 500 mK as the thermometer. The bolometer is voltage biased, and the current is measured by a superconducting quantum interference device (SQUID) ammeter

  14. Corrosion and Galvanic behavior of Copper, Carbon steeland Zinc Couples in (3.5 %wt) Nacl Solution

    OpenAIRE

    Qasim M. Abbas; Jamal M. Ali

    2009-01-01

    The galvanic corrosion of the (Cu - Fe), (Cu - Zn) and (Fe - Zn) couples have been investigated in 3.5% NaCl solution, 40ºC, different velocities (Re = 5000, 10000 and 15000) and different area ratios of cathode to anode (AR= 0.5,1 and 2), by using commercial metal pipe (cylindrical tube).The Zero Resistance Ammeter has been used to measure the galvanic current (Ig) and galvanic potential (Eg) with time. The galvanic current density increases with increasing velocity (Re) and the area ra...

  15. Improved Calibration of Instruments for Small Direct Currents

    CERN Document Server

    Scherer, Hansjörg; Krause, Christian

    2016-01-01

    We report on new calibration methods for picoammeters and low-current sources. The "Ultrastable Low-noise Current Amplifier" (ULCA) was used for the exemplary calibration of commercial state-of-the-art ammeter and current source instruments in the current range between 1 femtoampere and 1 microampere. The uncertainties achieved are compared with results obtained from two other calibration methods for small direct currents. It is shown that using the ULCA as calibrator allows achieving lower uncertainties together with the benefit of easier handling compared to alternative techniques. Also, the ULCA allows performing current meter and source calibrations between 1 femtoampere and 1 microampere with a single method.

  16. Galvanic Corrosion between Alloy 690 and Magnetite in Alkaline Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Soon-Hyeok Jeon

    2015-12-01

    Full Text Available The galvanic corrosion behavior of Alloy 690 coupled with magnetite has been investigated in an alkaline solution at 30 °C and 60 °C using a potentiodynamic polarization method and a zero resistance ammeter. The positive current values were recorded in the galvanic couple and the corrosion potential of Alloy 690 was relatively lower. These results indicate that Alloy 690 behaves as the anode of the pair. The galvanic coupling between Alloy 690 and magnetite increased the corrosion rate of Alloy 690. The temperature increase led to an increase in the extent of galvanic effect and a decrease in the stability of passive film. Galvanic effect between Alloy 690 and magnetite is proposed as an additional factor accelerating the corrosion rate of Alloy 690 steam generator tubing in secondary water.

  17. Corrosion and Galvanic behavior of Copper, Carbon steeland Zinc Couples in (3.5 %wt Nacl Solution

    Directory of Open Access Journals (Sweden)

    Qasim M. Abbas

    2009-01-01

    Full Text Available The galvanic corrosion of the (Cu - Fe, (Cu - Zn and (Fe - Zn couples have been investigated in 3.5% NaCl solution, 40ºC, different velocities (Re = 5000, 10000 and 15000 and different area ratio’s of cathode to anode (AR= 0.5,1 and 2, by using commercial metal pipe (cylindrical tube.The Zero Resistance Ammeter has been used to measure the galvanic current (Ig and galvanic potential (Eg with time. The galvanic current density increases with increasing velocity (Re and the area ratio (AR. The galvanic potential (Eg is shifted to less negative with increasing velocity (Re and the area ratio (AR. A statistical relations for the galvanic current density and galvanic potential as a function of (Re. and the area ratio had been created depending on Quasi-Newton method. There is good agreement between experimental and predicted results.

  18. Corrosion behavior of alloy 600 coupled with electrodeposited magnetite in simulated secondary water of PWRs

    International Nuclear Information System (INIS)

    The corrosion behavior of Alloy 600 coupled with magnetite was investigated in simulated secondary water of pressurized water reactors using a potentiodynamic polarization test and zero-resistance ammeter. Passive film formed on the surface of Alloy 600 was also analyzed using X-ray photoelectron spectroscopy. Alloy 600 was the anodic element of the galvanic pair since its corrosion potential was less noble than that of the magnetite. Galvanic coupling increased the corrosion current density of Alloy 600 due to the shifting of the potential of Alloy 600 to the positive value. The passive film of coupled Alloy 600 was more slowly stabilized and was thinner and less protective than that of non-coupled Alloy 600. (author)

  19. Coating Prospects in Corrosion Prevention of Aluminized Steel and Its Coupling with Magnesium

    Science.gov (United States)

    Sun, Fuyan

    In this study, a plasma electrolytic oxidation (PEO) process was used to form oxide coating on aluminized steel, heated aluminized steel and magnesium. A potentiodynamic polarization corrosion test was employed to investigate the general corrosion properties. Galvanic corrosion of steel samples and magnesium samples was studied by zero resistance ammeter (ZRA) tests and boiling tests. Scanning electron microscopy (SEM) and EDS were used to investigate the coating microstructure and the coating/substrate interface. In general, the PEO coatings on all three substrate can help prevent general corrosion. 6-min coated magnesium with unipolar current mode performs best in most galvanic couplings for preventing both general corrosion and galvanic corrosion. Factors which could influence galvanic corrosion behaviors of tested samples were discussed based on area ratios of anode/cathode and cell potential driving force during the ZRA corrosion tests and boiling tests.

  20. 改进电热法测定氯化钠溶液比热容的研究%Study on Using Improved Electrothermal Method to Test Specific Heat Capacity of Sodium Chloride Solution

    Institute of Scientific and Technical Information of China (English)

    付睿丽; 马镛; 李磊; 吴修治

    2014-01-01

    改进电热法测定比热容装置,省去电流表,用阻值恒定的 FeCrAl 合金电阻丝代替,并且设置静音搅拌叶轮,实现溶液自动搅拌。为防止氯化钠溶液电解,用石墨电极代替传统铜电极,测出氯化钠溶液比热容随浓度的变化规律:即在初温相同的条件下,氯化钠溶液比热容随浓度增加而线性降低;随着初始温度的升高,氯化钠溶液比热容随浓度变化曲线整体向上平移。%The experimental device,by which the improved electrothermal method is used to test the specific heat capacity,may leave out an ammeter,and the ammeter can be replaced by the re-sistance wire of FeCrAl Alloy which has constant resistance.The device has mute stirring impel-ler,and can mix the solution automatically.In order to prevent the sodium chloride solution from being electrolysed,the traditional copper electrode is replaced by graphite electrode.Then,the variations of the specific heat capacity of sodium chloride solution with the temperature are test-ed.The results of the experiment indicate that the specific heat capacity of sodium chloride solu-tion decreases linearly along with the increase of concentration,and with the changes of the initial temperature,the curve offset slightly.

  1. High density trans-admittance mammography development and preliminary phantom tests

    Directory of Open Access Journals (Sweden)

    Zhao Mingkang

    2012-09-01

    Full Text Available Abstract Background Malignant breast tumor tissue has a significantly different electrical impedance spectrum than surrounding normal tissues. This has led to the development of impedance imaging as a supplementary or alternative method to X-ray mammography for screening and assessment of breast cancers. However low spatial resolution and poor signal to noise ratio has limited the clinical application. Methods In order to improve spatial resolution we developed a trans-admittance mammography (TAM system including an array of 60×60 current sensing electrodes. We adopted a similar setup to X-ray mammography where the breast is situated between two holding plates. The top plate is a large solid metal electrode for applying a sinusoidal voltage over a range of frequencies from 50 Hz to 500 kHz. The bottom plate has 3600 current sensing electrodes that are kept at the ground potential. Currents are generated from the top voltage-applying electrode and spread throughout the breast, entering the TAM system through the array of current sensing electrodes on the bottom plate. The TAM system measures the exit currents through 6 switching modules connected to 600 electrodes each. Each switching module is connected to 12 ammeter channels which are switched sequentially to 50 of the 600 electrodes each measurement time. Each ammeter channel is comprised of a current-to-voltage converter, a gain amplifier, filters, an analog to digital converter, and a digital phase sensitive demodulator. Results We found an average noise level of 38 nA, amplitude stability of less than 0.2%, crosstalk of better than -60 dB and 70 dB signal to noise ratio over all channels and operating frequencies. Images were obtained in time difference and frequency difference modes in a saline phantom. Conclusion We describe the design, construction, and calibration of a high density TAM system in detail. Successful high resolution time and frequency difference images showed regions of

  2. Experimental Investigation of Micro Heat Pipes of Different Cross-Sections Having Same Hydraulic Diameter

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Effects of micro heat pipe (MHP) cross-sections and orientations on its thermal perforrnance are experimentally investigated in this study. Tests are conducted using five different cross-sections (circular, semicircular, elliptical,semi-elliptical and rectangular) of micro heat pipes having same hydraulic diameter of 3 mm placed at three different inclination angles (0°, 45°, 90°), where water is used as the working fluid. Evaporator section of the MHP is heated by an electric heater and the condenser section is cooled by circulation of water in an annular space between condenser section and the water jacket. Temperatures at different locations of the MHP are measured using five calibrated K type thermocouples. Heat supply is varied using a voltage regulator which is measured by a precision ammeter and a voltmeter. It is found that thermal performance tends to deteriorate as the MHP is flattened.Thus among all cross-sections of MHP, circular one exhibits the best thermal performance in terms of heat flux dissipation followed by semi-elliptical, semi-circular, elliptical and rectangular cross-sections. Moreover, its heat transfer capability also decreases with decreasing of its inclination angle. Finally, a correlation is developed which covers all the experimental data within +7%.

  3. A study of power availability in Oleh community in Isoko South local Government area of Delta state, Nigeria

    Directory of Open Access Journals (Sweden)

    S.O. Otuagoma

    2016-03-01

    Full Text Available In this study, the availability of electric power supply in the Oleh community of Isoko South Local Government Area of Delta State, Nigeria was carried out. The methods employed in achieving this include the use of Hour – Meter to register the number of hours supply was available for a period of three months, Multimeter and Ammeter were used to measure the supply voltage and current at any given time. The load shedding method adopted in the community by the Benin Electricity Distribution Company, BEDC, was also investigated. The results showed that power availability in the community for the three months under review was very bad. The average percentage of power available for the three months was 11.8%, meaning 88.2% of the time, power was unavailable. The power reliability index for each month of the study was negative; -5.94, -7.82 and -5.94 for June, July and August, 2015 respectively against a recommended value of high reliability of 0.989. This poor power availability accounts for the underdevelopment of the community.

  4. High-performance photoelectrochemical-type self-powered UV photodetector using epitaxial TiO₂/SnO₂ branched heterojunction nanostructure.

    Science.gov (United States)

    Li, Xiaodong; Gao, Caitian; Duan, Huigao; Lu, Bingan; Wang, Youqing; Chen, Lulu; Zhang, Zhenxing; Pan, Xiaojun; Xie, Erqing

    2013-06-10

    TiO₂/SnO₂ branched heterojunction nanostructure with TiO₂ branches on electrospun SnO2 nanofiber (B-SnO₂ NF) networks serves as a model architecture for efficient self-powered UV photodetector based on a photoelectrochemical cell (PECC). The nanostructure simultaneously offers a low degree of charge recombination and a direct pathway for electron transport. Without correcting 64.5% loss of incident photons through light absorption and scattering by the F-doped tin oxide (FTO) glass, the incident power conversion efficiency reaches 14.7% at 330 nm, more than twice as large as the nanocrystalline TiO₂ (TiO₂ NC, 6.4%)-film based PECC. By connecting a PECC to an ammeter, the intensity of UV light is quantified using the output short-circuit photocurrent density (J(sc)) without a power source. Under UV irradiation, the self-powered UV photodetector exhibits a high responsivity of 0.6 A/W, a high on/off ratio of 4550, a rise time of 0.03 s and a decay time of 0.01 s for J(sc) signal. The excellent performance of the B-SnO₂ NF-based PECC type self-powered photodetector will enable significant advancements for next-generation photodetection and photosensing applications.

  5. Fabrication and electromagnetic interference shielding effectiveness of polymeric composites filled with silver-coated microorganism cells

    International Nuclear Information System (INIS)

    In this paper, helical silver-coated Spirulina cells were used as conductive fillers for the fabrication of polymeric composites. The morphology and composition of the coated Spirulina cells were analyzed with scanning electron microscope and energy dispersive X-ray spectrometer. The densities of silver-coated Spirulina cells were measured using the standard Archimedes method with distilled water. The electrical resistivity was measured by four-probe technique using ammeter and voltmeter whereas electromagnetic interference shielding effectiveness was measured by four-port method using vector network analyzer and coaxial-airline sample holder. The results showed that the silver-coated Spirulina cells with different coating thickness were lightweight fillers compared to the other typical conductive particles. The polymeric composites could achieve good conductivity at the lower content of silver-coated Spirulina cells owing to their helical shape. The shielding effectiveness of polymeric composites had a strong dependence on their conductivity. At the coating thickness of 0.96 μm and the content of 40 vol%, the shielding effectiveness could reach above 74.3 dB in entire test wave band.

  6. Performance of a 4 Kelvin pulse-tube cooled cryostat with dc SQUID amplifiers for bolometric detector testing

    CERN Document Server

    Barron, Darcy; Keating, Brian; Quillin, Ron; Stebor, Nathan; Wilson, Brandon

    2013-01-01

    The latest generation of cosmic microwave background (CMB) telescopes is searching for the undetected faint signature of gravitational waves from inflation in the polarized signal of the CMB. To achieve the unprecedented levels of sensitivity required, these experiments use arrays of superconducting Transition Edge Sensor (TES) bolometers that are cooled to sub-Kelvin temperatures for photon-noise limited performance. These TES detectors are read out using low- noise SQUID amplifiers. To rapidly test these detectors and similar devices in a laboratory setting, we constructed a cryogenic refrigeration chain consisting of a commercial two-stage pulse-tube cooler, with a base temperature of 3 K, and a closed-cycle 3He/4He/3He sorption cooler, with a base temperature of 220 mK. A commercial dc SQUID system, with sensors cooled to 4 K, was used as a highly-sensitive cryogenic ammeter. Due to the extreme sensitivity of SQUIDs to changing magnetic fields, there are several challenges involving cooling them with puls...

  7. Recent development of anaerobic digestion processes for energy recovery from wastes.

    Science.gov (United States)

    Nishio, Naomichi; Nakashimada, Yutaka

    2007-02-01

    Anaerobic digestion leads to the overall gasification of organic wastewaters and wastes, and produces methane and carbon dioxide; this gasification contributes to reducing organic matter and recovering energy from organic carbons. Here, we propose three new processes and demonstrate the effectiveness of each process. By using complete anaerobic organic matter removal process (CARP), in which diluted wastewaters such as sewage and effluent from a methane fermentation digester were treated under anaerobic condition for post-treatment, the chemical oxygen demand (COD) in wastewater was decreased to less than 20 ppm. The dry ammonia-methane two-stage fermentation process (Am-Met process) is useful for the anaerobic treatment of nitrogen-rich wastes such as waste excess sludge, cow feces, chicken feces, and food waste without the dilution of the ammonia produced by water or carbon-rich wastes. The hydrogen-methane two-stage fermentation (Hy-Met process), in which the hydrogen produced in the first stage is used for a fuel cell system to generate electricity and the methane produced in the second stage is used to generate heat energy to heat the two reactors and satisfy heat requirements, is useful for the treatment of sugar-rich wastewaters, bread wastes, and biodiesel wastewaters. PMID:17368391

  8. VAPOR SPACE AND LIQUID/AIR INTERFACECORROSION TESTS

    Energy Technology Data Exchange (ETDEWEB)

    Zapp, P.; Hoffman, E.

    2009-11-09

    The phenomena of vapor space corrosion and liquid/air interface corrosion of carbon steel in simulated liquid waste environments have been investigated. Initial experiments have explored the hypothesis that vapor space corrosion may be accelerated by the formation of a corrosive electrolyte on the tank wall by a process of evaporation of relatively warmer waste and condensation of the vapor on the relatively cooler tank wall. Results from initial testing do not support the hypothesis of electrolyte transport by evaporation and condensation. The analysis of the condensate collected by a steel specimen suspended over a 40 C simulated waste solution showed no measurable concentrations of the constituents of the simulated solution and a decrease in pH from 14 in the simulant to 5.3 in the condensate. Liquid/air interface corrosion was studied as a galvanic corrosion system, where steel at the interface undergoes accelerated corrosion while steel in contact with bulk waste is protected. The zero-resistance-ammeter technique was used to measure the current flow between steel specimens immersed in solutions simulating (1) the high-pH bulk liquid waste and (2) the expected low-pH meniscus liquid at the liquid/air interface. Open-circuit potential measurements of the steel specimens were not significantly different in the two solutions, with the result that (1) no consistent galvanic current flow occurred and (2) both the meniscus specimen and bulk specimen were subject to pitting corrosion.

  9. Fabrication and electromagnetic interference shielding effectiveness of polymeric composites filled with silver-coated microorganism cells

    Energy Technology Data Exchange (ETDEWEB)

    Lan, Mingming, E-mail: lan_mingming@163.com [College of Mechanical and Electrical Engineering, Henan Agricultural University, Zhengzhou 450002 (China); Zhang, Deyuan; Cai, Jun; Hu, Yanyan; Yuan, Liming [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, School of Mechanical Engineering and Automation, Beihang University, Beijing 100191 (China)

    2014-07-01

    In this paper, helical silver-coated Spirulina cells were used as conductive fillers for the fabrication of polymeric composites. The morphology and composition of the coated Spirulina cells were analyzed with scanning electron microscope and energy dispersive X-ray spectrometer. The densities of silver-coated Spirulina cells were measured using the standard Archimedes method with distilled water. The electrical resistivity was measured by four-probe technique using ammeter and voltmeter whereas electromagnetic interference shielding effectiveness was measured by four-port method using vector network analyzer and coaxial-airline sample holder. The results showed that the silver-coated Spirulina cells with different coating thickness were lightweight fillers compared to the other typical conductive particles. The polymeric composites could achieve good conductivity at the lower content of silver-coated Spirulina cells owing to their helical shape. The shielding effectiveness of polymeric composites had a strong dependence on their conductivity. At the coating thickness of 0.96 μm and the content of 40 vol%, the shielding effectiveness could reach above 74.3 dB in entire test wave band.

  10. Voltage-Biased Superconducting Transition-Edge Bolometer with Strong Electrothermal Feedback Operated at 370 mK.

    Science.gov (United States)

    Lee, S F; Gildemeister, J M; Holmes, W; Lee, A T; Richards, P L

    1998-06-01

    We present an experimental study of a composite voltage-biased superconducting bolometer (VSB). The tested VSB consists of a Ti-film superconducting thermometer (T(c) ~375 mK) on a Si substrate suspended by NbTi superconducting leads. A resistor attached to the substrate provides calibrated heat input into the bolometer. The current through the bolometer is measured with a superconducting quantum interference device ammeter. Strong negative electrothermal feedback fixes the bolometer temperature at T(c) and reduces the measured response time from 2.6 s to 13 ms. As predicted, the measured current responsivity of the bolometer is equal to the inverse of the bias voltage. A noise equivalent power of 5 x 10(-17) W/ radicalHz was measured for a thermal conductance G ~ 4.7 x 10(-10) W/K, which is consistent with the expected thermal noise. Excess noise was observed for bias conditions for which the electrothermal feedback strength was close to maximum. PMID:18273298

  11. A superconducting bolometer with strong electrothermal feedback

    International Nuclear Information System (INIS)

    We present a theoretical analysis and experimental evaluation of a transition-edge superconducting bolometer for detecting infrared and millimeter waves. The superconducting film is voltage biased and the current is read by a superconducting quantum interference device ammeter. Strong electrothermal feedback maintains the sensor temperature within the transition, gives a current responsivity that is simply the inverse of the bias voltage, and reduces the response time by several orders of magnitude below the intrinsic time constant C/G. We evaluated a voltage-biased bolometer that operates on the Tc∼95 mK transition of a tungsten film with a thermal conductance of G∼1.2x10-9 W/K. As expected, the electrical noise equivalent power of 3.3x10-17/W√Hz is close to the thermal fluctuation noise limit and is lower than that of other technologies for these values of G and temperature. The measured time constant of 10 μs is ∼100 times faster than the intrinsic time constant. copyright 1996 American Institute of Physics

  12. Corrosion evaluation of multi-pass welded nickel–aluminum bronze alloy in 3.5% sodium chloride solution: A restorative application of gas tungsten arc welding process

    International Nuclear Information System (INIS)

    Highlights: • Corrosion of GTA welded nickel–aluminum bronze (C95800) was studied. • Drastic microstructural changes occurred during the welding operations. • The β′ and α phases acts as anode and cathode, correspondingly, in weld region. • A few nanoamperes couple current was measured in ZRA test as galvanic corrosion. • Corrosion resistance of weld parts could not be weakened in marine environments. - Abstract: In this research, the corrosion behavior of a gas tungsten arc welded nickel–aluminum bronze (NAB) alloy is investigated by DC and AC electrochemical techniques in 3.5% sodium chloride solution. Regarding the electrochemical impedance spectroscopy and potentiodynamic results, uniform corrosion resistance of instantly immersed weld and base samples are almost analogous and increased (more in weld region) during the immersion times. Moreover, zero resistant ammeter results demonstrated that the few nanoampere galvanic currents are attributed to microstructural and morphological differences between these two regions. Therefore, the welding procedure could not deteriorate the general corrosion resistance of the restored damaged NAB parts operating in marine environments

  13. Experimental Study on Rebar Corrosion Using the Galvanic Sensor Combined with the Electronic Resistance Technique

    Science.gov (United States)

    Xu, Yunze; Li, Kaiqiang; Liu, Liang; Yang, Lujia; Wang, Xiaona; Huang, Yi

    2016-01-01

    In this paper, a new kind of carbon steel (CS) and stainless steel (SS) galvanic sensor system was developed for the study of rebar corrosion in different pore solution conditions. Through the special design of the CS and SS electronic coupons, the electronic resistance (ER) method and zero resistance ammeter (ZRA) technique were used simultaneously for the measurement of both the galvanic current and the corrosion depth. The corrosion processes in different solution conditions were also studied by linear polarization resistance (LPR) and the measurements of polarization curves. The test result shows that the galvanic current noise can provide detailed information of the corrosion processes. When localized corrosion occurs, the corrosion rate measured by the ER method is lower than the real corrosion rate. However, the value measured by the LPR method is higher than the real corrosion rate. The galvanic current and the corrosion current measured by the LPR method shows linear correlation in chloride-containing saturated Ca(OH)2 solution. The relationship between the corrosion current differences measured by the CS electronic coupons and the galvanic current between the CS and SS electronic coupons can also be used to evaluate the localized corrosion in reinforced concrete. PMID:27618054

  14. Galvanic Corrosion of Coated Al Alloy Panels with More Noble Fasteners

    Science.gov (United States)

    Feng, Zhicao

    A test sample incorporating a painted Al alloy panel, uncoated through-hole fasteners, and scribes has been shown to provide accelerated response during atmospheric corrosion testing in the field and in laboratory chambers. Several different aspects of this test sample and the behavior of different coating systems are investigated in this dissertation. The galvanic current between SS316 or Ti-6Al-4V fasteners and painted and scribed AA7075-T6 panels was examined during exposure in a salt fog chamber using a zero-resistance ammeter. The anodic current of the AA7075-T6 panel and the cathodic current of each of the four fasteners were monitored using different connection schemes. The anodic current of the panel depended on the number of fasteners connected. The total cathodic current of fasteners was approximately equal to the anodic current of the AA7075-T6 panel, which validates the accuracy of the current measurement. Furthermore, galvanic interaction between the fasteners was observed such that the cathodic current of other fasteners was decreased when a new fastener was added to the measurement. Scribes on a panel can interact with distant fasteners, not just the closest ones. The amount of corrosion as determined by charge and optical profilometry were close and indicated SS316 fasteners caused more corrosion attack than Ti-6Al-4V fasteners. The galvanic current of an AA7075-T6 panel coupled with mixed SS316 and Ti-6Al-4V fasteners was monitored using a zero-resistance ammeter during 3 weeks exposure in an ASTM B117 chamber or immersed in 5 wt% NaCl solution. SS316 fasteners provided more cathodic current than Ti in both environments and the current in ASTM B117 was higher than in 5 wt% NaCl solution due to greater oxygen availability. The integral of the anodic current with time and optical profilometery (OP) analysis were used to assess the corrosion attack quantitatively for two different coating systems. An acceleration factor was defined to represent the

  15. The Integrated Demonstration Instrument of Peltier Effect and Seebeck Effect%珀尔帖效应与塞贝克效应综合演示仪

    Institute of Scientific and Technical Information of China (English)

    陈文娟; 薛德宽; 黄兴洲; 位浩杰; 刘冰

    2015-01-01

    A Peltier and Seebeck effects integrated demonstrator Design, which overcomes theflaws of traditional demonstrator only demonstrating an effect. DS18B20 temperature sensor and WH7016M temperature controller are used to control the cooling temperature,displaying cooling temperature on the computer by Lab-VIEW software. The voltmeter and ammeter show the voltage and current when TEC cooling and power genera-tion. It overcomes the weakness of other demonstrators not quantitative demonstration and only showing one effect. It also realizes the function of temperature change displayed by computer graphics. This instrument is a simple,stable performance,which achieves good results in the classroom demonstration.%设计制作了珀尔帖效应与塞贝克效应综合演示仪。采用 DS18B20温度传感器和WH7016M温度控制器控制制冷温度,利用LabVIEW软件在电脑上显示制冷温度变化曲线。通过电压表电流表显示温差半导体制冷和发电时的电压电流。该演示仪既克服了以往此类演示仪不能定量演示且只能演示一种效应的缺点,又实现了温度变化用计算机图形演示的功能。该仪器操作简单、性能稳定、效果明显,在课堂演示中取得了良好的效果。

  16. 基于LabVIEW的磁悬浮轴承的静态刚度测量系统%Measurement System of Static Stiffness for Magnetic Bearings Based on LabVIEW

    Institute of Scientific and Technical Information of China (English)

    马骁; 尹成科; 陈琛

    2012-01-01

    Rotors can be suspended in stators through electromagnetic force in magnetic bearings. The static stiffness is one important technical characteristic of magnetic bearings, so it is a necessary procedure to measure static stiffness for magnetic bearings. A static stiffness measurement system was established up for active magnetic bearings in the open-loop control. This system was based on LabVIEW software development platform, and included X - Y - Z precision motorized stages, six-axis force/torque transducer,laser optical displacement sensor,and high precision ammeter for the most part. An industrial personal computer controlled every measurement cell for automatic measurement, acquisition, and data storage. It has the advantage of high automation.%磁悬浮轴承主要利用电磁力使转子悬浮于定子中,其刚度特性是磁悬浮轴承的重要技术指标,因此磁悬浮轴承的刚度测量是检验磁悬浮轴承性能的必要环节.文中建立了适用于混合控制的磁悬浮轴承在开环控制下的静态刚度测量系统.该系统利用LabVIEW软件开发测量平台,由X-Y -Z电控精密位移台、六自由度力传感器、激光位移传感器及高分辨率电流表等设备组成,并由工控机统一控制各测量单元,实现自动测量、自动采集与数据存储等功能,具有自动化程度高的优点.

  17. A state of the art on electrochemical noise technique. Assessment of corrosion characteristics and development of remedial technology in nuclear materials

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong Jin; Kim, Joung Soo; Kim, Hong Pyo; Lim, Yun Soo; Yi, Yong Sun; Chung, Man Kyo

    2003-02-01

    The studies for the application of electrochemical noise technique were reviewed in terms of principle, analysing method and application examples of this technique. Because 4% of the economic damage of industry is caused by metallic corrosion, it is important to find and protect corrosive materials and location. By corrosion monitoring of industrial facilities such as nuclear power plant using Electrochemical Noise Measurement(ENM), corrosion attack can be detected and furthermore it can be indicated whether the attacked materials is replaced by new one or not. According to development of control and electronic technology, it was easy to apply ENM to the industry and the interest in ENM also increased. As corrosion is produced on a metal under corrosive environment, local anode(oxidation) and cathode(reduction) are formed. Hence, there is potential difference and current flow between the anode and cathode. ENM is monitoring the potential difference and the current flow with time by high impedance load voltmeter and Zero Resistance Ammeter(ZRA), respectively. The potential difference and current flow generated spontaneously without any application of current and potential between electrodes are monitored by electrochemical noise technique, Thereby ENM can be regarded as the most ideal corrosion monitoring method for the industrial facility and nuclear power plant having corrosion damage and difficulty in access of human body. Moreover, it is possible to obtain the spontaneous and reliable results from the metals damaged by ununiform and localized corrosion such as pitting and SCC using ENM while it is difficult to obtain the reliable result using traditional linear polarization and ac-impedance measurement. In many countries, there are extensive works concerned with application of electrochemical noise technique to corrosion monitoring of nuclear power plant and other industrial facilities, whereas there is little work on this field in Korea. Systematic study for

  18. Evaluation of the energy dependence of a zinc oxide nanofilm X-ray detector

    Energy Technology Data Exchange (ETDEWEB)

    Valenca, C.P.V., E-mail: claudia.cpvv@gmail.com [Universidade Federal de Pernambuco (UFPE), Recife (Brazil); Silveira, M.A.L.; Macedo, M.A., E-mail: odecamm@gmail.com [Universidade Federal de Sergipe (UFSE), Sao Cristovao, SE (Brazil); Santos, L.A.P, E-mail: lasantos@scients.com.br [Centro Regional de Ciencias Nucleares (CRCN-NE/CNEN-PE), Recife, PE (Brazil)

    2015-07-01

    International organizations of human health and radiation protection have recommended certain care for using of the X-ray as a diagnosis tool to avoid any type of radiological accident or overdose to the patient. This can be done assessing the parameters of the X-ray equipment and there are various types of detectors available for that: ionizing chamber, electronic semiconductor devices, etc. These detectors must be calibrated so that they can be used for any energy range and such a procedure is correlated with what is called the energy dependence of the detector. In accordance with the stated requirements of IEC 61267, the standard radiation quality beams and irradiation conditions (RQRs) are the tools and techniques for calibrating diagnostic X-Ray instruments and detectors. The purpose of this work is to evaluate the behavior of the energy dependence of a detector fabricated from a zinc oxide (ZnO) nanofilm. A Pantak industrial X-ray equipment was used to generate the RQR radiation quality beams and test three ZnO detector samples. A 6430 sub-femto-ammeter, Keithley, was used to bias the ZnO detector and simultaneously perform the output readings. The results showed that the ZnO device has some increase in its sensitivity to the ionizing radiation as the X-ray effective energy decreases unlike other types of semiconductor electronic devices typically used as an X-ray detector. We can conclude that the ZnO device can be used as a diagnostic X-ray detector with an appropriate calibration. (author)

  19. Heat Transfer of Single and Binary Systems inPool Boiling

    Directory of Open Access Journals (Sweden)

    Abbas J. Sultan

    2010-01-01

    Full Text Available The present research focuses on the study of the effect of mass transfer resistance on the rate of heat transfer in pool boiling. The nucleate pool boiling heat transfer coefficients for binary mixtures (ethanol-n-butanol, acetone-n-butanol, acetone-ethanol, hexane-benzene, hexane-heptane, and methanol-water were measured at different concentrations of the more volatile components. The systems chosen covered a wide range of mixture behaviors.The experimental set up for the present investigation includes electric heating element submerged in the test liquid mounted vertically. Thermocouple and a digital indictor measured the temperature of the heater surface. The actual heat transfer rate being obtained by multiplying the voltmeter and ammeter readings. A water cooled coil condenses the vapor produced by the heat input and the liquid formed returns to the cylinder for re-evaporation.The boiling results show that the nucleate pool boiling heat transfer coefficients of binary mixtures were always lower than the pure components nucleate pool boiling heat transfer coefficients. This confirmed that the mass transfer resistance to the movement of the more volatile component was responsible for decrease in heat transfer and that the maximum deterioration that was observed at a point was the absolute concentration differences between vapor and liquid phases at their maximum. All the data points were tested with the most widely known correlations namely those of Calus-Leonidopoulos, Fujita and Thome. It was found that Thome's correlation is the more representative form, for it gave the least mean and standard deviations

  20. Metering revisited - innovative concepts for electrical monitoring and reporting systems

    International Nuclear Information System (INIS)

    For the first three-quarters of this century, the monitoring of electrical power and energy has been dominated by conventional electromechanical voltmeters, ammeters, and watthour meters. Only in the last decade have solid state microprocessor-based distal devices become available for application in the commercial and industrial marketplace. These new devices perform the tasks of up to 24 conventional indicating meters for about the price of three. Communication via a RS-485 data link to a PC allows monitoring of up to 70 values including times and dates, min/max history, temperature indications, and energy management alarms. Complex waveform analysis can also be carried out for harmonic problems typically associated with adjustable speed drives that have been installed on fans and pumps for energy management savings. Since metering systems are absolutely essential to a successful Energy Management Process, consideration should be given to applying the latest in metering technology. It should be noted that meters by themselves do not save money, they only cost money to install and maintain. Proper monitoring, recording, and analysis lead to corrective actions which produce the desired result of reducing energy per unit of production or per service performed. Experience has shown that a 1 to 2% reduction can be achieved after meters are installed just by letting the users know that they are being monitored. Up to a 5% reduction can occur when the users then become proactive toward better managing of their energy. Ultimately up to 10% reduction can be achieved when metering is tied directly to the process through a PLC or DCS, in a closed loop automated process control arrangement

  1. REMOTE DIAGNOSTICS OF TURNOUTS STATE ON TIMING AND SPECTRAL COMPOSITION IN CURRENT CURVE

    Directory of Open Access Journals (Sweden)

    S. Yu. Buryak

    2015-03-01

    Full Text Available Purpose. Development and implementation the points system diagnostics that would allow determining remotely the current state of turnout with all possible faults, gradual and sudden failures, damages, and in real time to report about their appearance. Methodology. State diagnostics on the values analysis of turnout main parameters is proposed to carry out with the help of a computer and analog-to-digital converter (ADC. Connecting measurements performance is advisable to produce to a shunt ammeter, installed in the working circuit of the point feed panel. ADC converts the analog signal of lost volts at the shunt into digital form and transmits it to a computer which stores the received data on its own recording medium for their further processing and storage. There is special software that is capable to reconnect signal and construct its temporal characteristic as well as decompose it on the spectral components. Using it one can analyze the obtained data, which allows diagnosing state of points upon change the nature, values and composition of the current curve. Findings. The computer diagnosis method was confirmed in practice for possible indications of problems that are associated with both the mechanical part of the turnout and the electrical part of it, while controlling parameters such as the amount of current normal transition, when working on frictions, the duration of the transition, properly adjusted headset and attachment points, the state of the motor. Originality. The use of computer technology in the diagnosis of the state of turnouts during their operation to monitor the current values of technical indicators, analysis and storage for all types of electric switches with different types of engines both DC and AC occurs through digitization and recording signal from measuring shunt of point feeder panel. Practical value. The proposed method enables timely, still in the early stages of defect parts, damages or failures of nodes

  2. Research on the Temporal and Spatial Change of Irradiance inside the Greenhouse of Vegetable Planting%蔬菜大棚内辐照度时空变化研究

    Institute of Scientific and Technical Information of China (English)

    孙丽; 刘振威

    2011-01-01

    [Objective] The theoretic guidance for the high-yielding vegetable production in greenhouse was provided through the investigation.[Method] The temporal and spatial variation of the irradiance to vegetable planted in greenhouse was measured with TBQ-DL solar radiation ammeter and then analyzed. [Results]There was a single peak curve in the irradiance inside greenhouse in both cloudy and sunny day. The irradiance in cloudy day was weaker than that in sunny day and the maximum of the irradiance in cloudy day was at 14:00 and in sunny day, at 12:00. The irradiance gradually increased in either cloudy or sunny day with the height-increasing inside greenhouse. The order of the irradiance at the different parts inside greenhouse in both cloudy and sunny day was: east part>central part>west part in the morning and west part> central part> east part in the aftemoon.[Conclusion] The full use of sun light resource in the relevant high part in greenhouse in vegetable production, especially in the area with many more cloudy days, should be made.%[目的]为蔬莱大棚的高产栽培提供理论指导.[方法]利用TBQ-DL太阳辐射电流表对蔬菜大棚的辐照度时间和空间变化进行测定和研究.[结果]蔬菜大棚内阴天和睛天辐照度均呈单峰型曲线,阴天辐照度比晴天弱,阴天辐照度在14:00达到最大值,晴天在12:00达到最大值.阴天和晴天辐照度均随高度的升高呈递增趋势.阴天和晴天大棚不同部位辐照度规律均是:上午东侧>中侧>西侧,下午西侧>中侧>东侧.[结论]在生产中,尤其是阴天较多的地区,应该更充分利用蔬菜大棚高层的光照资源.

  3. 配位体交换-流动注射分析法测定水中有效氰化物%Determination of available cyanide in water by ligand exchange-flow injection analysis

    Institute of Scientific and Technical Information of China (English)

    乔小宇; 李华昌; 于力; 张萍

    2012-01-01

    A method for the determination of the available cyanide,namely, the total of cyanide including ions (CN-),HCN (aq),as well as zinc,copper,cadmium,mercury,nickel and silver cyanide complexes in water by ligand exchange reagents and CNSolution FS 3100 cyanide analyzer, has been studied. Gaseous HCN which was generated in the reaction module entered into alkaline absorption solution by gas diffusion diaphragm (GD) and was converted to cyanide ions (CN- ) ,and then was detected by ammeter in the flow testing pool. The interference of methanal, phenol, sodium hypochlorite, and sulfide to the determination of CN~ was inspected and removed. The experiment results indicated that, in the range of cyanide concentration between 2. 0-1 000 μg/L,r>0. 999 6;the detection limit of method was 0. 6 μg /L;the relative standard deviation (RSD) (n = 5) was smaller than 2. 5%,the recoveries of real samples were 92%-102%. It can be applied to detect the available cyanide in large a-mount of surface water,groundwater,drinking water and wastewater of petroleum chemical industry, metallurgy, electroplating, papermaking.%研究了采用配位体交换试剂和CNSolution FS 3100氰化物分析系统检测水中有效氰化物(即CN、HCN(aq)以及锌、铜、镉、汞、镍和银的氰络合物的总和)的分析方法.在反应模块中生成的气态HCN通过气体扩散膜片(GD)进入碱性吸收液中并转换为CN,然后进入流动检测池由安培计检测.考察了甲醛类化合物、苯酚化合物、次氯酸钠及硫化物等对CN测定的干扰及消除方法.实验结果表明,CN浓度在2.0~1 000 μg/L范围内,线性相关系数r>0.999 6;检出限为0.6 μg/L;RSD(n=5)<2.5%;实际样品加标回收率为92%~102%.该方法可应用于大批量地表水、地下水、饮用水及石油化工、冶金、电镀、造纸等行业废水中有效氰化物的测定.

  4. Basic functions of telecommunication channel elements for successful information transmission

    Directory of Open Access Journals (Sweden)

    Milorad S. Markagić

    2011-04-01

    Full Text Available The challenge in the field of multimedia telecommunications is an attempt to integrate texts, sound, images and videos coherently and consistently and to ensure simplicity and interactivity of operation. In order to make the proposed multimedia applications acceptable to end-users, the quality of transmission through the network and message presentation should have special attention. The main aims of this paper are the introduction to the communication channel with its basic elements, a detailed description of the information source and the presentation of possible approaches to the analysis of the telecommunication channel. Introduction In the age of mass application of various communication means, end-users of telecommunication channel elements rarely pay attention to the processes taking place in everyday communication and the elements presented in the channel. In order to discuss all the factors that influence the establishment and maintenance of the links, this paper will explain the basic elements of telecommunication channels. Source Every object that generates messages to be transferred to a recipient is called the source of the message. Directors, writers, speakers, books, newspapers, various instruments (thermometer, barometer, ammeter, etc., computers, a man himself - these are all sources of various messages. In relation to facilities that generate messages, there are different sources of messages. All the messages that they generate belong to discrete or continuous modes of messages. Discrete messages can be presented with element sets, where elements can be considered through different values of observed messages. Each text message of arbitrary length, for example, is made of a finite number of elements - symbols (letters, numbers, punctuation marks, from the set of symbols called the alphabet message source. Continuous messages can be presented with an infinite number of sets of elements where elements can have different values of

  5. Investigation of the chemical and electrochemical phenomena in the chemical mechanical planarization of copper

    Science.gov (United States)

    Wang, Ling

    uncoupled copper, tantalum and titanium electrodes were obtained in commercial slurry and solutions containing hydrogen peroxide and glycine, for assessing the polarity between copper and tantalum when forming a galvanic couple, as function of peroxide concentrations, solution pHs, and the impact of diluting the slurry on the galvanic interaction. Galvanic currents and mixed corrosion potentials were measured in tantalum-copper couples formed by short-circuiting the two specimen electrodes in a three-electrode cell through a potentiostat-based zero resistance ammeter, to verify the correlation between the polarity and the galvanic interactions and to assess the effects of solution composition and the tantalum-to-copper surface area ratio. The results showed that the material removal due to galvanic interaction under non-polishing conditions is negligibly small, but could be a potential issue during CMP, and either copper or tantalum barrier material could experience accelerated corrosion, depending on the solution composition. The galvanic interaction between copper and tantalum is sensitive to the solution composition. Acidic acetate/acetic acid buffer may transiently accelerate the galvanic corrosion of copper, while basic carbonate/bicarbonate buffer may transiently accelerate the galvanic corrosion of tantalum. Glycine promotes galvanic corrosion of copper. Hydrogen peroxide is the most effective component to exacerbate galvanic corrosion between copper and tantalum, with tantalum experiencing accelerated corrosion. Changing the surface area of tantalum, which has the more active corrosion, has a less significant effect on the galvanic corrosion than changing the surface areas of the copper, which has a more noble potential.

  6. Fundamentals of Physics, Part 3 (Chapters 22-33)

    Science.gov (United States)

    Halliday, David; Resnick, Robert; Walker, Jearl

    2004-03-01

    -4 Capacitors in Parallel and in Series. 25-5 Energy Stored in an Electric Field. 25-6 Capacitor with a Dielectric. 25-7 Dielectrics: An Atomic View. 25-8 Dielectrics and Gauss' Law. Review & Summary. Questions. Problems. Chapter 26. Current and Resistance. What precaution should you take if caught outdoors during a lightning storm? 26-1 What Is Physics? 26-2 Electric Current. 26-3 Current Density. 26-4 Resistance and Resistivity. 26-5 Ohm's Law. 26-6 A Microscopic View of Ohm's Law. 26-7 Power in Electric Circuits. 26-8 Semiconductors. 26-9 Superconductors. Review & Summary. Questions. Problems. Chapter 27. Circuits. How can a pit crew avoid a fire while fueling a charged race car? 27-1 What Is Physics? 27-2 "Pumping" Charges. 27-3 Work, Energy, and Emf. 27-4 Calculating the Current in a Single-Loop Circuit. 27-5 Other Single-Loop Circuits. 27-6 Potential Difference Between Two Points. 27-7 Multiloop Circuits. 27-8 The Ammeter and the Voltmeter. 27-9 RC Circuits. Review & Summary. Questions. Problems. Chapter 28. Magnetic Fields. How can a beam of fast neutrons, which are electrically neutral, be produced in a hospital to treat cancer patients? 28-1 What Is Physics? 28-2 What Produces a Magnetic Field? 28-3 The Definition of 736 :B. 28-4 Crossed Fields: Discovery of the Electron . 28-5 Crossed Fields: The Hall Effect. 28-6 A Circulating Charged Particle. 28-7 Cyclotrons and Synchrotrons. 28-8 Magnetic Force on a Current-Carrying Wire. 28-9 Torque on a Current Loop. 28-10 The Magnetic Dipole Moment. Review & Summary. Questions. Problems. Chapter 29. Magnetic Fields Due to Currents. How can the human brain produce a detectable magnetic field without any magnetic material? 29-1 What Is Physics? 29-2 Calculating the Magnetic Field Due to a Current. 29-3 Force Between Two Parallel Currents. 29-4 Ampere's Law. 29-5 Solenoids and Toroids. 29-6 A Current-Carrying Coil as a Magnetic Dipole. Review & Summary. Questions. Problems. Chapter 30. Induction and Inductance. How can the

  7. The Chemical and Educational Appeal of the Orange Juice Clock

    Science.gov (United States)

    Kelter, Paul B.; Carr, James D.; Johnson, Tanya; Mauricio Castro-Acuña, Carlos

    1996-12-01

    difference between the open circuit voltage (1.772 V) and the voltage with a known resistance (1.037 V). The difference, 1.772 - 1.037 = 0.735 V, equals the product of the circuit current and the resistance of the orange juice (ROJ), or ROJ = 0.735 V/0.001037 A = 708 Ohm 4. Finally, measure the current that the clock itself requires by hooking up in series an ammeter to the battery and the clock. The reading is not easy to take with an ammeter, which does not sample very often, and integrates across time. The computer interface works better for this. In our clock, a current of 0.49 mA was used. 5. The payoff comes at this point. The predicted voltage drop (I x Rint) can be calculated, voltage drop = I x Rint = 0.00049 A x 708 Ohm = 0.35 V Our observed voltage drops for this system were typically around 0.30 V. As a confirmation of the relationship of internal resistance to voltage drop, we placed the strips 1 mm apart in an orange by digging 2 holes in the orange and placing into the holes the coiled parts of the strips. We expected the voltage drop to be much higher than with the juice, due to the much higher internal resistance of the orange. Even when the strips were nearly touching, the drop was about 1 V. The Water Clock We discussed above the difference in the redox system when water is used rather than orange juice. Distilled water, which has a high internal resistance, will not permit the clock to run. However, hard tap water or distilled water with, for example, 1 g of table salt in 300 mL of water will work fine. As expected, because of the lower hydrogen ion concentration, the initial cell voltage is lower, typically around 1.45 V. The clock also ticks more slowly and more softly in water than in orange juice. In water, a black precipitate forms on the magnesium electrode and becomes more extensive with time. When the strip is removed from distilled water, and allowed to dry the precipitate turns white. Further student exploration on the precipitate might include