Section Three Building and Working with Electrostatic Equipment
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Role of Dielectric Materials in Electrical Engineering B D Bhagat
ISSN: 2319-5967 ISO 9001:2008 Certified International Journal of Engineering Science and Innovative Technology (IJESIT) Volume 2, Issue 5, September 2013 Role of Dielectric Materials in Electrical Engineering B D Bhagat Abstract- In India commercially industrial consumer consume more quantity of electrical energy which is inductive load has lagging power factor. Drawback is that more current and power required. Capacitor improves the power factor. Commercially manufactured capacitors typically used solid dielectric materials with high permittivity .The most obvious advantages to using such dielectric materials is that it prevents the conducting plates the charges are stored on from coming into direct electrical contact. I. INTRODUCTION Dielectric materials are those which are used in condensers to store electrical energy e.g. for power factor improvement in single phase motors, in tube lights etc. Dielectric materials are essentially insulating materials. The function of an insulating material is to obstruct the flow of electric current while the function of dielectric is to store electrical energy. Thus, insulating materials and dielectric materials differ in their function. A. Electric Field Strength in a Dielectric Thus electric field strength in a dielectric is defined as the potential drop per unit length measured in volts/m. Electric field strength is also called as electric force. If a potential difference of V volts is maintained across the two metal plates say A1 and A2, held l meters apart, then Electric field strength= E= volts/m. B. Electric Flux in Dielectric It is assumed that one line of electric flux comes out from a positive charge of one coulomb and enters a negative charge of one coulombs. -
Discovery of Radio Waves 1887 Static Electricity
Heinrich Hertz (1857 - 1894) Discovery of Radio Waves 1887 Static Electricity • Thales of Miletus (624 – 526 BC) – Two pieces of amber rubbed with wool or two pieces of glass rubbed with silk would repel each other. • We now know that the amber removes electrons from the wool and becomes negatively charged. • Similarly, the glass becomes positively charged, having given up electrons to the silk. – Also, the amber would be attracted to the glass and the wool to the silk. Static Electricity Magnetism • Thales of Miletus (624-526 BCE) • Described the lodestone • China in 100 BCE used the magnetic compass. • By convention, the direction of a magnetic field (S -> N) is indicated by a compass needle. Galileo Galilei (1564 – 1642) • One of the earliest “scientists”, dared to “tinker with nature”, rather than merely observing it. • Observed moons of Jupiter, and supported the Copernican hypothesis. Isaac Newton (1642 – 1727) • Invented calculus to describe gravitation. • Demonstrated that white light is a mixture of colours. • Postulated that light is a stream of corpuscles. • Invented the Newtonian telescope. Static Electricity • 1663 – The earliest friction machines rubbed a glass sphere against wool. • 1733 – Charles Francois du Fay (1698 – 1739) postulated that there were two kinds of electrical fluid – vitreous and resinous Static Electricity • 1733 – The Leyden jar invented in Holland could store charges from generators. • Spurred much research into static electricity. Static Electricity • Benjamin Franklin (1705 - 1790) • 1751 - Lightning was static electricity • Arbitrarily defined Vitreous as “positive” • Resinous, “negative” • Theory of charge conservation Static Electricity • Luigi Galvani (1737–1798) • 1770 - Discovered that static electricity from a Leyden jar could make frog’s legs twitch. -
The Stage Is Set
The Stage Is Set: Developments before 1900 Leading to Practical Wireless Communication Darrel T. Emerson National Radio Astronomy Observatory1, 949 N. Cherry Avenue, Tucson, AZ 85721 In 1909, Guglielmo Marconi and Carl Ferdinand Braun were awarded the Nobel Prize in Physics "in recognition of their contributions to the development of wireless telegraphy." In the Nobel Prize Presentation Speech by the President of the Royal Swedish Academy of Sciences [1], tribute was first paid to the earlier theorists and experimentalists. “It was Faraday with his unique penetrating power of mind, who first suspected a close connection between the phenomena of light and electricity, and it was Maxwell who transformed his bold concepts and thoughts into mathematical language, and finally, it was Hertz who through his classical experiments showed that the new ideas as to the nature of electricity and light had a real basis in fact.” These and many other scientists set the stage for the rapid development of wireless communication starting in the last decade of the 19th century. I. INTRODUCTION A key factor in the development of wireless communication, as opposed to pure research into the science of electromagnetic waves and phenomena, was simply the motivation to make it work. More than anyone else, Marconi was to provide that. However, for the possibility of wireless communication to be treated as a serious possibility in the first place and for it to be able to develop, there had to be an adequate theoretical and technological background. Electromagnetic theory, itself based on earlier experiment and theory, had to be sufficiently developed that 1. -
How to Make an Electret the Device That Permanently Maintains an Electric Charge by C
How to Make an Electret the Device That Permanently Maintains an Electric Charge by C. L. Strong Scientific America, November, 1960 Danger Level 4: (POSSIBLY LETHAL!!) Alternative Science Resources World Clock Synthesis Home --------------------- THE HISTORY OF SCIENCE IS A TREASURE house for the amateur experimenter. For example, many devices invented by early workers in electricity and magnetism attract little attention today because they have no practical application, yet these devices remain fascinating in themselves. Consider the so-called electret. This device is a small cake of specially prepared wax that has the property of permanently maintaining an electric field; it is the electrical analogue of a permanent magnet. No one knows in precise detail how an electret works, nor does it presently have a significant task to perform. George O. Smith, an electronics specialist of Rumson, N.J., points out, however, that this is no obstacle to the enjoyment of the electret by the amateur. Moreover, the amateur with access to a source of high-voltage current can make an electret at virtually no cost. "For more than 2,000 years," writes Smith, "it was suspected that the magnetic attraction of the lodestone and the electrostatic attraction of the electrophorus were different manifestations of the same phenomenon. This suspicion persisted from the time of Thales of Miletus (600 B.C.) to that of William Gilbert (A.D. 1600). After the publication of Gilbert's treatise De Magnete, the suspicion graduated into a theory that was supported by many experiments conducted to show that for every magnetic effect there was an electric analogue, and vice versa. -
2017 NSTA Physics Day Tutorial
NSTA Physics Day Baltimore, MD, Friday 6 Oct 2017, Hilton Key 9 Handout: Investigating Electrostatics with an Inexpensive Electrophorus Robert A. Morse, 5530 Nevada Ave, Washington DC 20015 [email protected] NSTA Baltimore, 6 Oct 2017 Abstract: An "instrumented" version of Volta's Electrophorus is a versatile tool to explore electrostatic charging by both induction and conduction, and highlights the difference between insulators and conductors. By adding some inexpensive indicators of charge state and charge transfer, it is a useful experimental context for students to use a qualitative atomic model to account for the observed phenomena. A classroom set is readily assembled from common household/grocery store materials at very low cost, and can be used in classes from middle school through introductory college. Participants will carry out a set of activities to get familiar with the construction and use of this historically important device. Participants - up to 40. Introduction: There are several ways to electrostatically charge objects. Many students have experience with charging by contact - by rubbing things - and have a simple model in which one object takes charge from another. Many students also have experience with induced charge effects such as sticking a rubbed balloon to a wall. Very few are likely to have observed or thought about the electrostatic charging of a conductor by the process of induction. In this workshop you will have an opportunity to see how a simple atomic model and inexpensive equipment can be used to guide students to an understanding of the process of electrostatic induction, using the concept of electrical action at a distance. -
Leyden Jars and Batteries According to Benjamin Franklin
eRittenhouse The Art of Making Leyden Jars and Batteries According to Benjamin Franklin Sara J. Schechner David P. Wheatland Curator of the Collection of Historical Scientific Instruments Department of the History of Science, Harvard University [email protected] Abstract The Leyden jar was arguably the most important instrument for electrical experiments in the second half of the 18th century, and Benjamin Franklin’s fame as a natural philosopher was based largely on his explanation of how it worked. In two remarkable letters written in the 1750s to scholars in Boston, Franklin offers instruction on the making of Leyden jars and assembling them into batteries. The letters also illustrate the challenges of getting and maintaining natural philosophical apparatus in colonial America, and a culture of recycling goods in order to make do. In the 1750s, Benjamin Franklin sent supplies and instructions for making Leyden jars to James Bowdoin, a Boston merchant and statesman interested in natural philosophy,1 and to John Winthrop, Hollis Professor of Mathematics and Natural Philosophy at Harvard College. Given the importance of Leyden jars to the development of Franklin’s own electrical theory, we are curious to know how Franklin made his own and what his recommendations might have been. The letters also illustrate the culture of repurposing goods and bricolage that was part of early modern science, particularly in the American colonies.2 1 James Bowdoin (1726-1790) was elected to the Massachusetts House of Representatives in 1753 and in 1757 began decades of service in the Council. His later leadership positions included governorship of the Commonwealth of Massachusetts in 1785-1787. -
Static Electricity Vocabulary Key Ideas Static Charge, P
09-SciProbe9-Chap09 2/8/07 10:47 AM Page 296 CHAPTER 9 Review Static Electricity Vocabulary Key Ideas static charge, p. 274 discharge, p. 274 Static electric charges can build up on objects. electrostatics, p. 274 • A static electric charge remains at rest until it is discharged. • A neutral object has an equal number of positive and negative charges. law of electric charges, p. 275 • Neutral objects can be given static charges that are either negative (by induced charge separation, p. 277 gaining electrons) or positive (by losing electrons). charging by friction, p. 279 Neutral objects are attracted to charged objects because of separation • charging by conduction, p. 279 of charges. charging by induction, p. 280 ؊ ؊ ؊ ؉ ؉ ؊ ؉ ؉ ؊ ؉ insulator, p. 282 ؊ ؉ ؊ ؉ ؊ ؉ ؉ ؉ ؊ ؊ ؊ ؊ ؊ ؊ ؉ ؉ ؉ ؉؊؉ conductor,p.282 grounded, p. 283 Van de Graaff generator, p. 285 electric force, p. 285 (a) a neutral (b) a sphere with a (c) a sphere with a positive sphere negative charge (more charge (fewer electrons Coulomb’s law, p. 286 electrons than protons) than protons) coulomb (C), p. 286 Objects become charged by friction, conduction, and induction. • Friction causes one object to gain electrons from another object. • Some materials, such as metals, are conductors of electricity, while other materials are insulators. • An object is charged by conduction when the excess charge on one object is transferred through contact to another object. • Induction occurs when a charged object influences the charge distribution in another object. 296 Unit C Electricity NEL 09-SciProbe9-Chap09 2/8/07 10:48 AM Page 297 An electric force between static charges can either attract or repel the charges. -
Lesson 04 Capacitors Inductors Antennas
Sierra College CIE-01 Jim Weir 530.272.2203 Lesson 04 [email protected] www.rstengineering.com/sierra Capacitors Inductors Antennas Capacitors A capacitor is two conductors separated by an insulator. That's pretty generic, isn't it? For example, you are a salt water sack (conductor) separated from your lab partner by an insulator (air). Does that make you two a capacitor? You bet. How about your automobile (steel) separated from the earth (conductor) by rubber tires? Yup (anybody old enough to remember "grounding straps"?). How about the earth and the moon separated by space? You bet. Going to the other extreme, how about two copper atoms separated by the "nothingness" of a billionth of an inch inside the copper molecule? You got it. One of the first capacitors was the Leyden jar, so named because it was invented by Pieter van Musschenbroek of the University of Leyden, Netherlands in 1745. It consisted of an outer metal shell, a glass jar, and an inner metal plate. Two brass conductors separated by a glass insulator. Because at the time it was thought to "condense" the "vapors of electricity" into a jar, it was originally called a "condenser", a name that was used for this electrical device up until the 1950s when the modern word capacitor became the preferred nomenclature. Page 1 of 16 Benjamin Franklin (late, of Philadelphia) did some experimentation with atmospheric static electricity. Franklin used the static electricity to first attract the small pith ball to the Leyden jar's "bell", and then after it was charged, it was repelled to the "grounding" bell, then reattracted to the jar bell, and so on until the static charge was dissipated. -
01. Franklin Intro 9/04
Franklin and Electrostatics- Ben Franklin as my Lab Partner A Workshop on Franklin’s Experiments in Electrostatics Developed at the Wright Center for Innovative Science Teaching Tufts University Medford MA 02155 by Robert A. Morse, Ph.D. ©2004 Sept 2004 Benjamin Franklin observing his lightning alarm. Described in Section VII. Engraving after the painting by Mason Chamberlin, R. A. Reproduced from Bigelow, 1904 Vol. VII Franklin and Electrostatics version 1.3 ©2004 Robert A. Morse Wright Center for Science Teaching, Tufts University Section I- page 1 Copyright and reproduction Copyright 2004 by Robert A. Morse, Wright Center for Science Education, Tufts University, Medford, MA. Quotes from Franklin and others are in the public domain, as are images labeled public domain. These materials may be reproduced freely for educational and individual use and extracts may be used with acknowledgement and a copy of this notice.These materials may not be reproduced for commercial use or otherwise sold without permission from the copyright holder. The materials are available on the Wright Center website at www.tufts.edu/as/wright_center/ Acknowledgements Rodney LaBrecque, then at Milton Academy, wrote a set of laboratory activities on Benjamin Franklin’s experiments, which was published as an appendix to my 1992 book, Teaching about Electrostatics, and I thank him for directing my attention to Franklin’s writing and the possibility of using his experiments in teaching. I would like to thank the Fondation H. Dudley Wright and the Wright Center for Innovative Science Teaching at Tufts University for the fellowship support and facilities that made this work possible. -
Until We Start to Deal with Atomic Nuclei and Sub-Nuclear Particles, All
7.3.1 ELECTROSTATICSM6,1 Until we start to deal with atomic nuclei and sub-nuclear particles, all the phenomena we observe in nature are explicable in terms of only two kinds of force2: gravitational and electromagnetic. The simplest manifestations of the electromagnetic force are familiar to most people. If you run a comb through your hair, it will attract tiny bits of paper and dust, not to mention leave your hair standing on end if it's very dry. A rubber balloon will stick to the wall if it is first rubbed on woollen clothing. Dust has an annoying tendency to stick to a newly polished table. In all of these cases we are dealing with forces between objects at rest. The electromagnetic forces between objects at rest are called electric forces, and the science that deals with them is called electrostatics. 7.3.1.1 Electric Charge3 Any objects that attract others in the way described above are said to possess an electric charge. Electric charge is a characteristic of subatomic particles, and is quantised. When expressed as a multiple of the so-called elementary charge e, electrons have a charge of −1. Protons have the opposite charge of +1. Quarks have a fractional charge of −1/3 or +2/3. The antiparticle equivalents of these have the opposite charge. There are other charged particles. The electric charge of a macroscopic object is the sum of the electric charges of its constituent particles. Often, the net electric charge is zero, since naturally the number of electrons in every atom is equal to the number of the protons, so their charges cancel out. -
SIS Bulletin Index Issues 1 to 80
Scientific Instrument Society Bulletin of the Scientific Instrument Society Index No 1 to No 80 Scientific Instrument Society Bulletin of the Scientific Instrument Society Index No 1 to No 80 Contents Introduction Index of Topics 3 Index of Articles 37 Index of Book Reviews 51 The Scientific Instrument Society 61 Documents Associated with the Index 61 Introduction Development of the Index of the Bulletin of the Scientific Instrument Society The first 40 issues of the Bulletin were indexed successively, ten issues at a time. With the advent of No 50 it was decided to amalgamate the earlier work and create a single index for all 50 issues. The work involved was a vast undertaking requiring the use of optical character recognition and other computer techniques on the earlier work, and a good deal of careful proof reading. The final product was handsomely produced in A4 size uniform with the Bulletin, running to 64 index pages. Having reached 80 issues, a similar combining exercise has been done, but with fewer categories within the Index. However, whilst the main index of individual topics remains as comprehensive as previously it is presented in a smaller typeface and makes use of more columns. At the time of printing, consideration is being given to the use of this new Index as a facility on the Society's website and also in connection with CDROMs of the Bulletin. Notes for using the 3 sections of the Bulletin Index, Issue No 1 to Issue No 80 Index of Topics Topics are arranged alphabetically by subject. References are shown as 'Issue No : Page No' eg 2:15 or 45:7-11 Index of Articles Authors of articles are listed alphabetically with the titles of their articles following in issue order. -
A Companion to Physics in the Enlightenment - Part 2
A Companion to Physics in the Enlightenment - part 2 Slides 3-4 give a short summary of the most important events in the history of electricity and magnetism. Slide 5. One of the chapters in De magnete by William Gilbert (1600) contains the first modern account of electrical studies. As the court physician to Queen Elisabeth Gilbert had access to her treasury. He decided to check how many different materials, including precious stones and gems, could be electrified by rubbing in the same way as amber. He provided himself with the first electroscope, a device to show the presence of electric charge on a nearby body: „Make yourself a rotating needle, versorium, of any sort of metal, three or four fingers long, pretty light, and poised on a sharp point after the manner of a magnetic pointer. Bring near to one end of it a piece of amber or a gem, lightly rubbed, polished and shining: at once the instrument revolves...” By making use of the versorium Gilbert was able to divide all studied materials into „electrics” (those which could be electrified by rubbing), and „non-electrics”. He introduced these terms by taking example of the Greek name for amber - ήλεκτρον. He also recognized several differences between magnetic and electric interactions. e.g. that lodestone attracts only iron whereas amber acts on many kinds of bodies, that the magnet attracts only towards its poles, amber - everywhere, that the magnet pulls heavier weights than amber can. Slide 6 shows several examples of early graphic representation of magnetic field; the concept of the field did not yet exist.