A Simple Atmospheric Electrical Instrument for Educational Use
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Alessandro Volta and the Discovery of the Battery
1 Primary Source 12.2 VOLTA AND THE DISCOVERY OF THE BATTERY1 Alessandro Volta (1745–1827) was born in the Duchy of Milan in a town called Como. He was raised as a Catholic and remained so throughout his life. Volta became a professor of physics in Como, and soon took a significant interest in electricity. First, he began to work with the chemistry of gases, during which he discovered methane gas. He then studied electrical capacitance, as well as derived new ways of studying both electrical potential and charge. Most famously, Volta discovered what he termed a Voltaic pile, which was the first electrical battery that could continuously provide electrical current to a circuit. Needless to say, Volta’s discovery had a major impact in science and technology. In light of his contribution to the study of electrical capacitance and discovery of the battery, the electrical potential difference, voltage, and the unit of electric potential, the volt, were named in honor of him. The following passage is excerpted from an essay, written in French, “On the Electricity Excited by the Mere Contact of Conducting Substances of Different Kinds,” which Volta sent in 1800 to the President of the Royal Society in London, Joseph Banks, in hope of its publication. The essay, described how to construct a battery, a source of steady electrical current, which paved the way toward the “electric age.” At this time, Volta was working as a professor at the University of Pavia. For the excerpt online, click here. The chief of these results, and which comprehends nearly all the others, is the construction of an apparatus which resembles in its effects viz. -
Parallel-Plate Capacitor
EXPERIMENT E4: Parallel-Plate Capacitor Objectives: • Scientific: Learn about parallel-plate capacitors • Scientific: Learn about multiple capacitors connected in parallel • Skill development: Use curve fitting to find parameters from experimental data Copyright © 2002, The University of Iowa Rev. jg 22 July 2002 Exp. E4: Parallel-Plate Capacitor Introductory Material Capacitance is a constant of proportionality. It relates the potential difference V between two conductors to their charge, Q. The charge Q is equal and opposite on the two conductors. The relationship can be written: Q = CV (4.1) The capacitance C of any two conductors depends on their size, shape, and separation. + schematic symbols capacitor battery One of the simplest configurations is a pair of flat conducting plates, which is called a “parallel-plate capacitor.” Theoretically, the capacitance of parallel-plate capacitors is CP = ε0 A/ d (4.2) where the subscript “P” denotes “parallel plate.” Here, A is the area of one of the plates, d is the distance between them, and ε0 is a constant called the “permittivity of free space,” which has a value of 8.85 × 10-12 C2 / N-m2, in SI units. Here is the basic idea of the experiment you will do. Suppose that you had a parallel-plate capacitor with the plates separated initially by a distance d0, and you applied a charge Q0 to the electrodes, so that they initially have a potential V0 = Q0 / Cp. Suppose that you then arranged for the two electrodes to be electrically insulated, so that the charge Q could not go anywhere. What would happen if you then increased the electrode separation d? The charge would remain constant, because it has nowhere to flow, whereas the capacitance would decrease, as shown in Eq. -
Made to Measure. Practical Guide to Electrical Measurements in Low Voltage Switchboards V
Contact us A 250 500 200 150 V (b) 100 (a) 50 0 t Made to measure. Practical guide to electrical measurements in low voltage switchboards A 250 500 ABB SACE The data and illustrations are not binding. We reserve 200 the right to modify the contents of this document on the 150 Una divisione di ABB S.p.A. basis of technical development of the products, 100 Apparecchi Modulari without prior notice. 50 0 Viale dell’Industria, 18 Copyright 2010 ABB. All rights reserved. - 1.500 - CAL. 20010 Vittuone (MI) Tel.: 02 9034 1 Fax: 02 9034 7609 bol.it.abb.com www.abb.com V 80 V 60 2CSC445012D0201 - 12/2010 (f) 40 50 Hz 20 0 t Made to measure. Practical guide to electrical measurements in low voltage switchboards table of Made to measure. Practical guide to electrical measurements contents in low voltage switchboards 1 Electrical measurements 5.3.2 Current transformers ......................................................... 37 5.3.3 Voltage transformers ......................................................... 38 1.1 Why is it important to measure? .......................................... 3 5.3.4 Shunts for direct current .................................................... 38 1.2 Applicational contexts .......................................................... 4 1.3 Problems connected with energy networks ......................... 4 6 The measurements 1.4 Reducing consumption ........................................................ 7 1.5 Table of charges .................................................................. 8 6.1 TRMS Measurements -
Keithley Instrumentation for Electrochemical Test Methods and Applications ––
Keithley Instrumentation for Electrochemical Test Methods and Applications –– APPLICATION NOTE Keithley Instrumentation for Electrochemical Test Methods and Applications APPLICATION NOTE With more than 60 years of measurement expertise, Keithley Cyclic Voltammetry Instruments is a world leader in advanced electronic test Cyclic voltammetry (CV), a type of potential sweep method, instrumentation. Our customers are scientists and engineers is the most commonly used electrochemical measurement in a wide range of research and industrial applications, technique, which typically uses a 3-electrode cell. Figure including many electrochemistry tests. Keithley manufactures 1 illustrates a typical electrochemical measurement circuit products that can source and measure current and voltage made up of an electrochemical cell, an adjustable voltage accurately. Electrochemistry disciplines that employ source (V ), an ammeter (A ), and a voltmeter (V ). The Keithley instrumentation include battery and energy storage, S M M three electrodes of the electrochemical cell are the working corrosion science, electrochemical deposition, organic electrode (WE), the reference electrode (RE), and the counter electronics, photo-electrochemistry, material research, electrode (CE). The voltage source (V ) for the potential sensors, and semiconductor materials and devices. Table 1 S scan is applied between the WE and CE. The potential (E) lists some of the test methods and applications that employ between the RE and WE is measured with the voltmeter, and Keithley products. the overall voltage (VS) is adjusted to maintain the desired Table 1. Electrochemistry test methods and applications potential at the WE with respect to the RE. The resulting Methods and Measurement current (i) flowing to or from the WE is measured with the Capabilities Applications ammeter (AM). -
Speed Limit: How the Search for an Absolute Frame of Reference in the Universe Led to Einstein’S Equation E =Mc2 — a History of Measurements of the Speed of Light
Journal & Proceedings of the Royal Society of New South Wales, vol. 152, part 2, 2019, pp. 216–241. ISSN 0035-9173/19/020216-26 Speed limit: how the search for an absolute frame of reference in the Universe led to Einstein’s equation 2 E =mc — a history of measurements of the speed of light John C. H. Spence ForMemRS Department of Physics, Arizona State University, Tempe AZ, USA E-mail: [email protected] Abstract This article describes one of the greatest intellectual adventures in the history of mankind — the history of measurements of the speed of light and their interpretation (Spence 2019). This led to Einstein’s theory of relativity in 1905 and its most important consequence, the idea that matter is a form of energy. His equation E=mc2 describes the energy release in the nuclear reactions which power our sun, the stars, nuclear weapons and nuclear power stations. The article is about the extraordinarily improbable connection between the search for an absolute frame of reference in the Universe (the Aether, against which to measure the speed of light), and Einstein’s most famous equation. Introduction fixed speed with respect to the Aether frame n 1900, the field of physics was in turmoil. of reference. If we consider waves running IDespite the triumphs of Newton’s laws of along a river in which there is a current, it mechanics, despite Maxwell’s great equations was understood that the waves “pick up” the leading to the discovery of radio and Boltz- speed of the current. But Michelson in 1887 mann’s work on the foundations of statistical could find no effect of the passing Aether mechanics, Lord Kelvin’s talk1 at the Royal wind on his very accurate measurements Institution in London on Friday, April 27th of the speed of light, no matter in which 1900, was titled “Nineteenth-century clouds direction he measured it, with headwind or over the dynamical theory of heat and light.” tailwind. -
High Resistance Measurements Introduction
1689 App Note 312 11/10/05 11:12 AM Page 1 Number 312 Application Note High Resistance Series Measurements Introduction R Resistance is most often measured with a digital multimeter, which can make measurements up to about 200MΩ. However, in some cases, resistances in the gigohm and higher ranges must be HI measured accurately. These cases include such applications as VA characterizing high megohm resistors, determining the resistivity of insulators and measuring the insulation resistance of printed LO circuit boards. These measurements are made by using an elec- trometer, which can measure both very low current and high Figure 1: The constant voltage method for measuring resistance impedance voltage. Using an electrometer, resistances up to constant current sources so that either the constant voltage or the 1018Ω can be measured depending on the method used. One method is to source voltage and measure current and the other constant current method can be used to measure high resistance. method is to source current and measure voltage. Besides using For accurate measurements, the high impedance terminal the proper method and instrumentation, special measurement of the ammeter is always connected to the high impedance point techniques such as shielding and guarding must be used to mini- of the circuit being measured. If not, erroneous measurements mize leakage current, noise and other undesirable effects that can may result. degrade the accuracy of the measurements. Some of the applications which use this method include: testing two-terminal high resistance devices, measuring insula- tion resistance, and determining the volume and surface resistivi- Measurement Methods ty of insulating materials. -
Electronic Voltmeters and Ammeters - Alessandro Ferrero, Halit Eren
ELECTRICAL ENGINEERING – Vol. II - Electronic Voltmeters and Ammeters - Alessandro Ferrero, Halit Eren ELECTRONIC VOLTMETERS AND AMMETERS Alessandro Ferrero Dipartimento di Elettrotecnica, Politecnico di Milano, Italy Halit Eren Curtin University of Technology, Perth, Western Australia Keywords: currents, voltages, measurements, standards, analog voltmeters, digital voltmeters, microvoltmeters, oscilloscopes Contents 1. Introduction. 2. Analog Meters 2.1. DC Analog Voltmeters and Ammeters 2.2. AC Analog Voltmeters and Ammeters 2.3. True rms Analog Voltmeters 3. Digital Meters 3.1. Dual-Slope DVMs 3.2. Successive-Approximation ADCs 3.3. AC Digital Voltmeters and Ammeters 3.4. Frequency Response of AC Meters 4. Radio-Frequency Microvoltmeters 5. Vacuum-Tube Voltmeters and Oscilloscopes 5.1. Analog Oscilloscopes 5.2. Digital Storage Oscilloscopes (DSOs) 5.3. Portable Oscilloscopes 5.4. High-Voltage Oscilloscopes Appendix Glossary Bibliography Biographical Sketches Summary Voltage UNESCOand current measurements are – esse EOLSSntial parts of engineering and science. Instruments that measure voltages and currents are called voltmeters and ammeters, respectively. ThereSAMPLE are two distinct types of voltmeterCHAPTERS and ammeter, which differ from each other by the operating principle that they are based on: electromechanical instruments and electronic instruments, which also include oscilloscopes. Electromechanical voltmeters and ammeters, including thermal-type instruments, represent early technology, but still are used in many applications. Basic elements of voltages and currents from the basic physical principles have been introduced in the electromechanical voltage and current measurements section. Also, voltage and currents standards have been dealt with in detail in other articles. ©Encyclopedia of Life Support Systems (EOLSS) ELECTRICAL ENGINEERING – Vol. II - Electronic Voltmeters and Ammeters - Alessandro Ferrero, Halit Eren In this article, modern electronic voltmeters and ammeters are discussed. -
Electrical Measurements
Name ________________________ Group #_______ Date _________ Partners ______________________ Electrical Measurements Experimental Objective The objective of this experiment is to become familiar with some of the electrical instruments. You will gain experience by wiring a simple electrical circuit and drawing its circuit diagram. You will learn the correct use of a digital multimeter as an ohmmeter, voltmeter and ammeter. Theory Current, I, is the flow of charge, measured in amps. Voltage, V, is the difference in electrical potential between two points, measured in volts. Resistance is the ratio of voltage across to the current flowing through it, measured in ohms, Ω. V R = I Wires are conductors with very low resistance designed to carry the current from one object to another. Resistors are objects with a moderately high resistance made of carbon films. Resistors are color coded to indicate the magnitude. A circuit diagram is a diagram that represents the electrical circuit using internationally accepted symbols. The diagram represents the electrical connections of the circuit, but not necessarily the bench layout of each item. A series connection consists of two or more components that are connected end to end with one another and the same current flows through each component. A parallel connection consists of components connected so that one end of all the components are connected together and the other ends are connected together such that the same voltage is applied across each component. Multimeters are used to measure current, voltage and resistance. The meters used in our lab will give you a digital reading and since they use a battery should always be turned off when not in use. -
An Oscillating - Magnet Watt Balance
An Oscillating - Magnet Watt Balance H. Ahmedov TÜBİTAK, UME, National Metrology Institute of Turkey E-mail:[email protected] Abstract We establish the principles for a new generation of simplified and accurate watt balances in which an oscillating magnet generates Faraday’s voltage in a stationary coil. A force measuring system and a mechanism providing vertical movements of the magnet are completely independent in an oscillating magnet watt balance. This remarkable feature allows to establish the link between the Planck constant and a macroscopic mass by a one single experiment. Weak dependence on variations of environmental and experimental conditions, weak sensitivity to ground vibrations and temperature changes, simple force measuring procedure, small sizes and other useful features offered by the novel approach considerable reduce the complexity of the experimental setup. We formulate the oscillating-magnet watt balance principle and establish the measurement procedure for the Planck constant. We discuss the nature of oscillating-magnet watt balance uncertainties and give a brief description of the Ulusal Metroloji Enstitüsü ( UME ) watt balance apparatus. 1. Introduction In 1975 Kibble described the principles of the first moving-coil watt balance [1,2], a two-part experiment which links the electrical and mechanical Sİ units by indirect conversion of electrical power into mechanical power. The watt balance principle and macroscopic electrical quantum effects: the Josephson effect and the quantum Hall effect [3, 4] established the link between a macroscopic mass and the Planck constant, the fundamental constant of the microworld [ 5 ]. This link provides a potential route to the redefinition of the kilogram [6, 7], the last base unit which is still defined by a manmade object, the international prototype of the kilogram. -
Experiment 0 an Introduction to the Equipment
Experiment 0 An Introduction to the Equipment Objectives After completing Experiment 0, you should be able to: • Use basic electronic instruments • Determine the precision of a measurement • Select the scale that gives the most accurate reading • Give a qualitative description of electric potential (voltage), current, and resistance • Describe the uses of an electrometer, voltmeter, ammeter, ohmmeter, and multimeter • Use an electrometer and digital multimeter properly • Describe the precautions required to protect meters from damage. Introduction In Physics 116L, you will investigate the properties of electricity and magnetism with a variety of laboratory instruments. Unlike mechanics, for which the basic measurements of length, time, and mass are familiar, common quantities, electricity and magnetism involve unfamiliar quantities and require special instruments for their study. Some of the measurements are quite simple, for example the circuits of Experiments 5 and 6, but others are more subtle. Although you are certainly familiar with certain aspects of basic electricity -- shocks upon touching metal objects on dry days, the quantitative experiments are not trivial. You must understand a number of physical processes and phenomena to form a conceptual picture of what is happening in these experiments. We cannot explore electrostatics one step at a time as in the lectures; understanding even the simplest experiments requires the complete framework of electrostatics. These first three experiments, which introduce you to electrical instruments and the basic properties of electric charge, require considerable thought and care. If you are unfamiliar with these instruments, you may find them slightly intimidating at first. However, they are not really difficult to use. This first "experiment" is merely a set of exercises to enable you to experiment with the basic instruments and become comfortable with using them. -
Basic Electrical Measurements
3 Basic Electrical Measurements 3.1 Electromechanical measuring devices current is delivered to the coil by two springs – these springs are also used as the mechanisms generating There are several advantages of traditional returning torque for the pointer. electromechanical instruments: simplicity, reliability, low price. The most important advantage is that the majority of such instruments can work without any additional power supply. Since people’s eyes are sensitive to movement also this psycho-physiological aspect of analogue indicating instruments (with moving pointer) is appreciated. On the other hand, there are several drawbacks associated with electromechanical analogue indicating instruments. First of all, they do not provide output signal, thus there is a need for operator’s activity during the measurement (at least for the reading of an indicated value). Another drawback is that such instruments generally use moving mechanical parts, which are sensitive to shocks, aging or wearing out. Relatively low price of moving pointer instruments FIGURE 3.1 today is not as advantageous as earlier, because on the The example of moving coil indicating instrument (1- moving coil, 2 – market there are available also very cheap digital permanent magnet, 3 – axle, 4 – pointer, 5 – bearings, 6 – spring, 7 – correction of zero). measuring devices with virtual pointer. Regrettably, it can be stated that most of the The moving coil is placed into the gap between the electromechanical analogue instruments are rather of magnet poles and soft iron core, shaped in such a way poor quality. In most cases these instruments are not as to produce uniform magnetic field. The movement able to measure with uncertainty better than 0.5%. -
High Accuracy Electrometers
www.keithley.com HighHigh accuracyaccuracy electrometerselectrometers forfor lowlow current/highcurrent/high resistanceresistance applicationsapplications A GREATER MEASURE OF CONFIDENCE KEITHLEY INSTRUMENTS ARE AT WORK AROUND THE WORLD KEITHLEY INSTRUMENTS ARE AT 1EΩ 1PΩ µ 1TΩ 1 C 1GΩ 1nC 1MΩ 1kΩ 1pC 1Ω 6430 6517 6514 1mΩ 1fC Resistance Measurement Ranges 6514 6517A Charge Measurement Ranges 1kV 1A 1mA 1V 1µA 1nA 1mV 1pA 1fA 1µV 1aA 6430 6517/6514 6430 6517/6514 Voltage Measurement Ranges Current Measurement Ranges High performance electrometers MEASUREMENTS FAR BEYOND THE RANGE OF CONVENTIONAL INSTRUMENTATION MEASUREMENTS FAR Keithley has more than a half-century of experience in designing and producing sensitive instrumentation. As new testing requirements have evolved, we’ve developed dozens of different models to address our customers’ needs for higher resolution, accuracy, and sensitivity, as well as support for specific applications. Keithley electrometers are at work around the world in production test applications, industrial R&D centers, and university and government laboratories—wherever people need to make high precision current, voltage, resistance, or charge measurements. What is an electrometer? Why is low voltage burden critical? Essentially, an electrometer is a highly refined digital multimeter Voltage burden is the voltage that appears across the ammeter (DMM). Electrometers can be used for virtually any measurement input terminals when measuring. As Figure 1 illustrates, a DMM task that a conventional DMM can and offer the advantages of uses a shunt ammeter that requires voltage (typically 200mV) to very high input resistance when used as voltmeters, and ultra-low be developed across a shunt resistor in order to measure current.