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The Invention of the Electric Motor History and Demonstration

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The Invention of the Electric Motor History and Demonstration 5/30/2019 Final - Google Docs The Invention of the Electric Motor History and Demonstration An Interactive Qualifying Project Submitted to the Faculty of WORCESTER POLYTECHNIC INSTITUTE in partial fulfilment of the requirements for the Degree of Bachelor of Science Authors: Barry Aslanian Sam Milender Jianqing Zhu Date Submitted: May 30, 2019 Report Submitted to: Professor John A. Goulet Worcester Polytechnic Institute 1 https://docs.google.com/document/d/1YlHwEPaMzsIsGJDuPXhYHf5dSh_0UfVAkvVOjNytLoQ/edit# 1/29 5/30/2019 Final - Google Docs Abstract The purpose of this project is to help high school level students learn about the basics of electromagnetism, and the history behind the subject. This document contains the fundamental concepts of the physics behind an electric motor and provides a comprehensive background of the history of electromagnetism. The topics in electromagnetism were demonstrated by creating a working replica of Thomas Davenport’s original DC motor, based on his 1837 patent. The building process is described and illustrated in this document to enhance the educational experience. Acknowledgements Our team would like to thank our project advisor, John Goulet, for providing us with necessary materials and helping us along the way throughout the building process and Ryan Breuer for being invaluable in learning how to forge the magnet cores. 2 https://docs.google.com/document/d/1YlHwEPaMzsIsGJDuPXhYHf5dSh_0UfVAkvVOjNytLoQ/edit# 2/29 5/30/2019 Final - Google Docs Executive Summary There are many great minds behind the invention of the electric motor. All of the early pioneers that discovered the uses of electricity and magnetism deserve credit for the work they did, and the foundations they have laid for those who came after them. Thomas Davenport, the inventor of the electric motor, is often forgotten, but it was he who made the monumental discovery of creating constant mechanical power from electromagnetism. This is one of the most important discoveries in all of science, and deserves significant recognition. The first section is a historical background of electromagnetism that can aid in sparking a student’s interest in the subject. It starts with William Gilbert and his experiments with the compass in the late 1500s, and goes through the contributions of Alessandro Volta, Hans Christian Ørsted, André-Marie Ampère, and Joseph Henry, all of which formed the foundation on which Davenport built his motor. It is helpful to know how these discoveries were made, and it is only proper to give credit to the individuals who discovered this physics that has led to the invention that benefits humanity so much today. Studying the physics behind an electric motor is a fantastic learning experience for anybody interested in electricity and magnetism. This document contains descriptions of some of the fundamental concepts behind an electric motor. The Right-Hand Rule is used to illustrate how the flow of electrical current in a wire interacts with a magnetic field to create a force. The form of each component within an electric motor is described along with a basic description of what they do. Using the right-hand rule, the description of the components, and a simple two-pole motor as an example, it is straightforward to understand how each component fits together within the electric motor to create the desired motion. The current goes through a brush into the commutator and through the armature poles, which produces a force as per the right hand rule. When the armature reaches the point where this force no longer has a tangential component (and therefore no longer induces rotational motion), the commutator stops the current flow through the armature, and only resumes it once the armature’s inertia has carried it to the point where the electromagnetic force would again have a tangential component. When current is resumed, the commutator has caused the current to invert direction through the poles, causing the force to also invert, and enable a constant rotational motion The motor replica represents a perfect project for students to complete to reinforce the electromagnetic concepts they learn in physics. This re-creation was completed how Davenport would have created his original, completely by hand from raw material, before the assembly into a functioning motor. A student would benefit from an in-class project of the assembly of a motor, as it was an incredibly beneficial project in deepening the understanding of electromagnetism. 3 https://docs.google.com/document/d/1YlHwEPaMzsIsGJDuPXhYHf5dSh_0UfVAkvVOjNytLoQ/edit# 3/29 5/30/2019 Final - Google Docs Table of Contents Abstract 2 Acknowledgements 2 Executive Summary 3 Table of Contents 4 Table of Figures 6 Introduction 7 The History of Electromagnetism 7 William Gilbert 7 Alessandro Volta 8 Hans Christian Ørsted and André-Marie Ampère 9 Joseph Henry 9 Thomas Davenport 10 Understanding the Electromagnet 10 Applying for the patent 11 After the invention 11 Model Railroad 12 Death 13 The Physics of the Electric Motor 14 Electric Current and Magnetic Fields 14 Composition of a Motor 15 Field Magnets 15 Armature 16 Poles 16 The Commutator and Brushes 16 The Physics 17 Building the Motor 20 In the Forge 20 The Wrought Iron Billet 20 The Final Shaping 22 The Frame 24 The Armature 24 The Brushes and Commutator 24 4 https://docs.google.com/document/d/1YlHwEPaMzsIsGJDuPXhYHf5dSh_0UfVAkvVOjNytLoQ/edit# 4/29 5/30/2019 Final - Google Docs The Finished Motor 25 Education 26 Conclusion 27 Authorship 28 Bibliography 28 5 https://docs.google.com/document/d/1YlHwEPaMzsIsGJDuPXhYHf5dSh_0UfVAkvVOjNytLoQ/edit# 5/29 5/30/2019 Final - Google Docs Table of Figures Figure 1: J oseph Henry’s Electromagnet 9 Figure 2: M ap of Thomas Davenport’s Locations 10 Figure 3: First Electric Motor 1837 US Patent 11 Figure 4: Davenport’s Electric Railway Model 12 Figure 5: The Direction of a Magnetic Field 14 Figure 6: The Right-Hand Rule 14 Figure 7: Composition of a DC brushed motor 15 Figure 8: Basic Electric Motor Diagram 17 Figure 9: Electromagnetic Forces that Induce a Rotational Motion. 18 Figure 10: E lectromagnetic Forces that would not Induce a Rotational Motion 18 Figure 11: The Split Between Commutator Pads 19 Figure 12: T he Electromagnetic Forces 19 Figure 13: Clean, Partially Clean, and Uncleaned Pieces of Wrought Iron 21 Figure 14: T he Welded Wrought Iron Billet 21 Figure 15: T he Now-Broken Billet of Wrought Iron 22 Figure 16: F orging Together the Two Pieces of the Armature Cores 23 Figure 17: T he Final Shape of the Armature and Field Cores 23 Figure 18: Finished Motor Showing Field Windings and Armature Windings 25 Figure 19: A Replica of Davenport’s Motor from the Smithsonian 26 6 https://docs.google.com/document/d/1YlHwEPaMzsIsGJDuPXhYHf5dSh_0UfVAkvVOjNytLoQ/edit# 6/29 5/30/2019 Final - Google Docs Introduction Electromagnetism is a difficult subject for a student to master. Even with a teacher with an established curriculum and a working knowledge of the subject, it is incredibly difficult to conceptualize electricity and magnetism, how they work together as a single force, and how to apply this force for everyday life. Despite how difficult it is to teach and understand, there were individuals who originally discovered the phenomena of magnetism and then electricity, all without a reference or teacher of any sort. These individuals, representing some of the brightest people humanity has ever seen, conducted numerous experiments, tested numerous hypotheses, and were able to set humanity on the path to the level of technological sophistication it has today. One of the best ways to go about assisting students in understanding electromagnetism is to re-create the experiments those electromagnetic pioneers conducted many years ago that allowed them to become the first people to truly begin to understand it. One of the most basic and most important of electronic devices is the electric motor. It demonstrates electrical flow, the creation and interaction of electromagnetic fields, and, most importantly, how all of those things are applicable in everyday life. The construction of one of these motors would be an incredibly useful project for students to complete during their study of electromagnetism. This project attempts a re-creation of the very first electric motor, created by a man by the name of Thomas Davenport in the early 1800s, and goes significantly more in depth into the history and process of the design of the motor than the average high school physics student would need to get in class, but it also serves as a proof-of-concept: such a re-creation deepens the creator’s understanding of the physics behind it, and having a physical object demonstrating the theory taught assists in cementing those same topics. The History of Electromagnetism It all started with the invention of the compass. The very first compasses are attributed to Song dynasty in around 1040 CE [1][2], where a scholar by the name of Shen Kuo wrote that, by rubbing a needle on a lodestone (naturally magnetized piece of magnetite) and suspending by a thread in a calm environment, it will always point south. The first European compass is commonly attributed to 14th century merchants in Amalfi [3], an important trade hub in the south of the Italian peninsula, although its European origin is not definitely known. It was one of the inventions, along with ocean-faring ships, that allowed the rise of the European colonial and trade empires. It was also the invention that began studies into the field of electromagnetism. William Gilbert It was in the late 16th century that a man by the name of William Gilbert began to experiment, and more importantly, document his experiments, with electromagnetism. It was thought by many that compass needles were attracted to Polaris, the north star, or to mountains in the north [4].
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