Solenoids, Electromagnets and Electromagnetic Windings
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Glossary Physics (I-Introduction)
1 Glossary Physics (I-introduction) - Efficiency: The percent of the work put into a machine that is converted into useful work output; = work done / energy used [-]. = eta In machines: The work output of any machine cannot exceed the work input (<=100%); in an ideal machine, where no energy is transformed into heat: work(input) = work(output), =100%. Energy: The property of a system that enables it to do work. Conservation o. E.: Energy cannot be created or destroyed; it may be transformed from one form into another, but the total amount of energy never changes. Equilibrium: The state of an object when not acted upon by a net force or net torque; an object in equilibrium may be at rest or moving at uniform velocity - not accelerating. Mechanical E.: The state of an object or system of objects for which any impressed forces cancels to zero and no acceleration occurs. Dynamic E.: Object is moving without experiencing acceleration. Static E.: Object is at rest.F Force: The influence that can cause an object to be accelerated or retarded; is always in the direction of the net force, hence a vector quantity; the four elementary forces are: Electromagnetic F.: Is an attraction or repulsion G, gravit. const.6.672E-11[Nm2/kg2] between electric charges: d, distance [m] 2 2 2 2 F = 1/(40) (q1q2/d ) [(CC/m )(Nm /C )] = [N] m,M, mass [kg] Gravitational F.: Is a mutual attraction between all masses: q, charge [As] [C] 2 2 2 2 F = GmM/d [Nm /kg kg 1/m ] = [N] 0, dielectric constant Strong F.: (nuclear force) Acts within the nuclei of atoms: 8.854E-12 [C2/Nm2] [F/m] 2 2 2 2 2 F = 1/(40) (e /d ) [(CC/m )(Nm /C )] = [N] , 3.14 [-] Weak F.: Manifests itself in special reactions among elementary e, 1.60210 E-19 [As] [C] particles, such as the reaction that occur in radioactive decay. -
Electromagnetism What Is the Effect of the Number of Windings of Wire on the Strength of an Electromagnet?
TEACHER’S GUIDE Electromagnetism What is the effect of the number of windings of wire on the strength of an electromagnet? GRADES 6–8 Physical Science INQUIRY-BASED Science Electromagnetism Physical Grade Level/ 6–8/Physical Science Content Lesson Summary In this lesson students learn how to make an electromagnet out of a battery, nail, and wire. The students explore and then explain how the number of turns of wire affects the strength of an electromagnet. Estimated Time 2, 45-minute class periods Materials D cell batteries, common nails (20D), speaker wire (18 gauge), compass, package of wire brad nails (1.0 mm x 12.7 mm or similar size), Investigation Plan, journal Secondary How Stuff Works: How Electromagnets Work Resources Jefferson Lab: What is an electromagnet? YouTube: Electromagnet - Explained YouTube: Electromagnets - How can electricity create a magnet? NGSS Connection MS-PS2-3 Ask questions about data to determine the factors that affect the strength of electric and magnetic forces. Learning Objectives • Students will frame a hypothesis to predict the strength of an electromagnet due to changes in the number of windings. • Students will collect and analyze data to determine how the number of windings affects the strength of an electromagnet. What is the effect of the number of windings of wire on the strength of an electromagnet? Electromagnetism is one of the four fundamental forces of the universe that we rely on in many ways throughout our day. Most home appliances contain electromagnets that power motors. Particle accelerators, like CERN’s Large Hadron Collider, use electromagnets to control the speed and direction of these speedy particles. -
Electromagnetism
EINE INITIATIVE DER UNIVERSITÄT BASEL UND DES KANTONS AARGAU Swiss Nanoscience Institute Electromagnetism Electricity and magnetism are two aspects of the same phenomenon: electromagnetism. A moving electric charge (in other words, an electric current) generates a magnetic field. Every electromagnet consists of a coil, which is nothing more than a tightly wound wire. Many electromagnets also have an iron core to make the magnetic field stronger. The more times the wire is wound around the coil, the stronger the magnetic field produced by the same current. Demonstration: Using electric current to create a magnetic field What you’ll need • a large sheet of paper on which to conduct the experiment • a sheet of stiff card or plexiglass • two batteries connected in series • a coil of copper wire • iron filings • crocodile clips (optional) • a small piece of iron (e.g. a screw) to place inside the coil (iron core) Instructions 1. Position the coil so that you can easily access the two ends of the wire and connect them to the battery. I used crocodile clips to attach them to the battery contacts, but you could also use wooden clothes pegs or electrical tape. 2. Connect the two batteries in series (+ - + - ). 3. Place the plexiglass or card over the coil. 4. When the electrical circuit is closed, slowly scatter the iron filings on top. What happens? The iron filings arrange themselves along the magnetic field lines. If you look closely, you can make out a pattern. Turn a screw into an electromagnet What you’ll need • a long iron screw or nail • two pieces of insulated copper wire measuring 15 and 30 cm • two three-pronged thumb tacks • a metal paperclip • a small wooden board • pins or paperclips • a 4.5 V battery Instructions Switch 1. -
Electromagnetic Induction, Ac Circuits, and Electrical Technologies 813
CHAPTER 23 | ELECTROMAGNETIC INDUCTION, AC CIRCUITS, AND ELECTRICAL TECHNOLOGIES 813 23 ELECTROMAGNETIC INDUCTION, AC CIRCUITS, AND ELECTRICAL TECHNOLOGIES Figure 23.1 This wind turbine in the Thames Estuary in the UK is an example of induction at work. Wind pushes the blades of the turbine, spinning a shaft attached to magnets. The magnets spin around a conductive coil, inducing an electric current in the coil, and eventually feeding the electrical grid. (credit: phault, Flickr) 814 CHAPTER 23 | ELECTROMAGNETIC INDUCTION, AC CIRCUITS, AND ELECTRICAL TECHNOLOGIES Learning Objectives 23.1. Induced Emf and Magnetic Flux • Calculate the flux of a uniform magnetic field through a loop of arbitrary orientation. • Describe methods to produce an electromotive force (emf) with a magnetic field or magnet and a loop of wire. 23.2. Faraday’s Law of Induction: Lenz’s Law • Calculate emf, current, and magnetic fields using Faraday’s Law. • Explain the physical results of Lenz’s Law 23.3. Motional Emf • Calculate emf, force, magnetic field, and work due to the motion of an object in a magnetic field. 23.4. Eddy Currents and Magnetic Damping • Explain the magnitude and direction of an induced eddy current, and the effect this will have on the object it is induced in. • Describe several applications of magnetic damping. 23.5. Electric Generators • Calculate the emf induced in a generator. • Calculate the peak emf which can be induced in a particular generator system. 23.6. Back Emf • Explain what back emf is and how it is induced. 23.7. Transformers • Explain how a transformer works. • Calculate voltage, current, and/or number of turns given the other quantities. -
Axial Field Permanent Magnet Machines with High Overload Capability for Transient Actuation Applications
THE UNIVERSITY OF SHEFFIELD Axial field permanent magnet machines with high overload capability for transient actuation applications By Jiangnan Gong A Thesis submitted for the degree of Doctor of Philosophy Department of Electronic and Electrical Engineering The University of Sheffield. JANUARY 2018 ABSTRACT This thesis describes the design, construction and testing of an axial field permanent magnet machine for an aero-engine variable guide vane actuation system. The electrical machine is used in combination with a leadscrew unit that results in a minimum torque specification of 50Nm up to a maximum speed of 500rpm. The combination of the geometry of the space envelope available and the modest maximum speed lends itself to the consideration of an axial field permanent magnet machines. The relative merits of three topologies of double-sided permanent magnet axial field machines are discussed, viz. a slotless toroidal wound machine, a slotted toroidal machine and a yokeless axial field machine with separate tooth modules. Representative designs are established and analysed with three-dimensional finite element method, each of these 3 topologies are established on the basis of a transient winding current density of 30A/mm2. Having established three designs and compared their performance at the rated 50Nm point, further overload capability is compared in which the merits of the slotless machine is illustrated. Specifically, this type of axial field machine retains a linear torque versus current characteristic up to higher torques than the other two topologies, which are increasingly affected by magnetic saturation. Having selected a slotless machine as the preferred design, further design optimization was performed, including detailed assessment of transient performance. -
Magnetic Fields
Welcome Back to Physics 1308 Magnetic Fields Sir Joseph John Thomson 18 December 1856 – 30 August 1940 Physics 1308: General Physics II - Professor Jodi Cooley Announcements • Assignments for Tuesday, October 30th: - Reading: Chapter 29.1 - 29.3 - Watch Videos: - https://youtu.be/5Dyfr9QQOkE — Lecture 17 - The Biot-Savart Law - https://youtu.be/0hDdcXrrn94 — Lecture 17 - The Solenoid • Homework 9 Assigned - due before class on Tuesday, October 30th. Physics 1308: General Physics II - Professor Jodi Cooley Physics 1308: General Physics II - Professor Jodi Cooley Review Question 1 Consider the two rectangular areas shown with a point P located at the midpoint between the two areas. The rectangular area on the left contains a bar magnet with the south pole near point P. The rectangle on the right is initially empty. How will the magnetic field at P change, if at all, when a second bar magnet is placed on the right rectangle with its north pole near point P? A) The direction of the magnetic field will not change, but its magnitude will decrease. B) The direction of the magnetic field will not change, but its magnitude will increase. C) The magnetic field at P will be zero tesla. D) The direction of the magnetic field will change and its magnitude will increase. E) The direction of the magnetic field will change and its magnitude will decrease. Physics 1308: General Physics II - Professor Jodi Cooley Review Question 2 An electron traveling due east in a region that contains only a magnetic field experiences a vertically downward force, toward the surface of the earth. -
PLL Approach to Mitigate Symmetrical Faults in Weak AC Grid of DFIG Based Wind Turbine for Voltage Stability Analysis
International Journal of Electrical Electronics & Computer Science Engineering Volume 5, Issue 2 (April, 2018) | E-ISSN : 2348-2273 | P-ISSN : 2454-1222 Available Online at www.ijeecse.com PLL Approach to Mitigate Symmetrical Faults in Weak AC Grid of DFIG Based Wind Turbine for Voltage Stability Analysis Cholleti Sriram1, O. Rakesh2, M. Harish3, A. Sridhar4 1Assistant Professor, 2-4UG Scholars, EEE Department, Guru Nanak Institute of Technology, Hyderabad, India [email protected], [email protected] Abstract: Study of Instability issues of the grid-connected of wind turbines (WTs) based on doubly fed induction doubly fed induction generator (DFIG) based wind turbines generators (DFIG) that intends to improve its low- (WTs) during low-voltage ride-through (LVRT) have got voltage ride through(LVRT) capability. The main little attention yet. In this paper, the small-signal behavior of objective of this work is to design an algorithm that DFIG WTs attached to weak AC grid with high impedances would enable the system to control the initial over during the period of LVRT is investigated, with special attention paid to the rotor-side converter (RSC). Firstly, currents that appear in the generator during voltage based on the studied LVRT strategy, the influence of the sags, which can damage the RSC, without tripping it. high-impedance grid is summarized as the interaction As a difference with classical solutions, based on the between phase-looked loop (PLL) and rotor current installation of crowbar circuits, this operation mode controller (RCC). As modal analysis result indicates that the permits to keep the inverter connected to the generator, underdamped poles are dominated by PLL, complex torque something that would permit the injection of power to coefficient method (CTCM), which is conventionally applied the grid during the fault, as the new grid codes demand. -
Lecture 8: Magnets and Magnetism Magnets
Lecture 8: Magnets and Magnetism Magnets •Materials that attract other metals •Three classes: natural, artificial and electromagnets •Permanent or Temporary •CRITICAL to electric systems: – Generation of electricity – Operation of motors – Operation of relays Magnets •Laws of magnetic attraction and repulsion –Like magnetic poles repel each other –Unlike magnetic poles attract each other –Closer together, greater the force Magnetic Fields and Forces •Magnetic lines of force – Lines indicating magnetic field – Direction from N to S – Density indicates strength •Magnetic field is region where force exists Magnetic Theories Molecular theory of magnetism Magnets can be split into two magnets Magnetic Theories Molecular theory of magnetism Split down to molecular level When unmagnetized, randomness, fields cancel When magnetized, order, fields combine Magnetic Theories Electron theory of magnetism •Electrons spin as they orbit (similar to earth) •Spin produces magnetic field •Magnetic direction depends on direction of rotation •Non-magnets → equal number of electrons spinning in opposite direction •Magnets → more spin one way than other Electromagnetism •Movement of electric charge induces magnetic field •Strength of magnetic field increases as current increases and vice versa Right Hand Rule (Conductor) •Determines direction of magnetic field •Imagine grasping conductor with right hand •Thumb in direction of current flow (not electron flow) •Fingers curl in the direction of magnetic field DO NOT USE LEFT HAND RULE IN BOOK Example Draw magnetic field lines around conduction path E (V) R Another Example •Draw magnetic field lines around conductors Conductor Conductor current into page current out of page Conductor coils •Single conductor not very useful •Multiple winds of a conductor required for most applications, – e.g. -
Transformed E&M I Homework Magnetic Vector Potential
Transformed E&M I homework Magnetic Vector Potential (Griffiths Chapter 5) Magnetic Vector Potential A Question 1. Vector potential inside current-carrying conductor Lorrain, Dorson, Lorrain, 15-1 pg. 272 Show that, inside a straight current-carrying conductor of radius R, µ Ι ρ 2 Α = 0 (1− ) 2π R 2 If A is set equal to zero at ρ = R. Question 2. Multipoles, dipole moment The vector potential of a small current loop (a magnetic dipole) with magnetic moment µ0 m × rˆ m is A = 2 4π r A) Assume that the magnetic dipole is at the origin and the magnetic moment is aligned with the +z axis. Use the vector potential to compute the B-field in spherical coordinates. B) Show that your expression for the B-field in part (a) can be written in the coordinate- € µ 1 0 ˆ ˆ free form B(r) = 3 3(m⋅r)r − m 4π r Note: The easiest way to do this one is by assuming the coordinate-free form and then showing that you get your expression in part (a) if you define your z axis to lie along m, rather than trying to go the other way around. Coordinate free formulas are nice, because now you can find B for more general situations. Question 3. Vector Potential of infinite sheet Lorrain, Dorson; Example, Pair of Long Parallel Currents pg. 252 Figure 14-10 shows two long parallel wires separated by a distance D and carrying equal currents I in opposite directions. To calculate A, we use the above result for the A of a single wire and add the two vector potentials: µ Ι L L A = 0 (ln − ln ) (14-37) 2π ρ a ρb Do Bx, By, and Bz at midpoint stretch? Question 4. -
Design and Optimization of Printed Circuit Board Inductors for Wireless Power Transfer System
University of Tennessee, Knoxville TRACE: Tennessee Research and Creative Exchange Engineering -- Faculty Publications and Other Faculty Publications and Other Works -- EECS Works 4-2013 Design and Optimization of Printed Circuit Board Inductors for Wireless Power Transfer System Ashraf B. Islam University of Tennessee - Knoxville Syed K. Islam University of Tennessee - Knoxville Fahmida S. Tulip Follow this and additional works at: https://trace.tennessee.edu/utk_elecpubs Part of the Electrical and Computer Engineering Commons Recommended Citation Islam, Ashraf B.; Islam, Syed K.; and Tulip, Fahmida S., "Design and Optimization of Printed Circuit Board Inductors for Wireless Power Transfer System" (2013). Faculty Publications and Other Works -- EECS. https://trace.tennessee.edu/utk_elecpubs/21 This Article is brought to you for free and open access by the Engineering -- Faculty Publications and Other Works at TRACE: Tennessee Research and Creative Exchange. It has been accepted for inclusion in Faculty Publications and Other Works -- EECS by an authorized administrator of TRACE: Tennessee Research and Creative Exchange. For more information, please contact [email protected]. Circuits and Systems, 2013, 4, 237-244 http://dx.doi.org/10.4236/cs.2013.42032 Published Online April 2013 (http://www.scirp.org/journal/cs) Design and Optimization of Printed Circuit Board Inductors for Wireless Power Transfer System Ashraf B. Islam, Syed K. Islam, Fahmida S. Tulip Department of Electrical Engineering and Computer Science, University of Tennessee, Knoxville, USA Email: [email protected] Received November 20, 2012; revised December 20, 2012; accepted December 27, 2012 Copyright © 2013 Ashraf B. Islam et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. -
THP40 Proceedings of the 12Th International Workshop on RF Superconductivity, Cornell University, Ithaca, New York, USA Cavity Region Is Less Than 40 Mt
Proceedings of the 12th International Workshop on RF Superconductivity, Cornell University, Ithaca, New York, USA Magnetic Field Studies in the ISAC-II Cryomodule R.E Laxdal, B. Boussier, K. Fong, I. Sekachev, G. Clark, V. Zvyagintsev, TRIUMF∗, Vancouver, BC, V6T2A3, Canada, R. Eichhorn, FZ-Juelich, Germany Abstract The medium beta section of the ISAC-II Heavy Ion Ac- celerator consists of five cryomodules each containing four quarter wave bulk niobium resonators and one supercon- ducting solenoid. The 9 T solenoid is not shielded but is equipped with bucking coils to reduce the magnetic field in the neighbouring rf cavities. A prototype cryomodule has been designed and assembled at TRIUMF. The cryomod- ule vacuum space shares the cavity vacuum and contains a mu-metal shield, an LN2 cooled, copper, thermal shield, plus the cold mass and support system. Several cold tests have been done to characterize the cryomodule. Early op- erating experience with a high field solenoid inside a cry- omodule containing SRF cavities will be given. The re- sults include measurements of the passive magnetic field in the cryomodule. We also estimate changes in the magnetic Figure 1: Cryomodule top assembly in the assembly frame field during the test due to trapped flux in the solenoid. prior to the cold test. Residual field reduction due to hysteresis cycling of the solenoid has been demonstrated. ISAC-II CAVITIES INTRODUCTION The ISAC-II medium beta cavity design goal is to op- erate up to 6 MV/m across an 18 cm effective length with TRIUMF is now preparing a new heavy ion supercon- Pcav ≤ 7 W. -
Electromagnetism Fall 2018 (Adapted from Student Guide for Electric Snap Circuits by Elenco Electronic Inc.)
VANDERBILT STUDENT VOLUNTEERS FOR SCIENCE http://studentorgs.vanderbilt.edu/vsvs Electromagnetism Fall 2018 (Adapted from Student Guide for Electric Snap Circuits by Elenco Electronic Inc.) Here are some Fun Facts for the lesson Wind turbines generate electricity by using the wind to turn their blades. These drive magnets around inside coils of electric wire Electromagnets are used in junk yards to pick up cars and other heavy metal objects Electromagnetics are used in home circuit breakers, door bells, magnetic door locks, amplifiers, telephones, loudspeakers, PCs, medical imaging, tape recorders Magnetic levitation trains use very strong electromagnets to carry the train on a cushion of magnetic repulsion. Floating reduces friction and allows the train to run more efficiently. Materials 16 sets (of 2) D-batteries in holder 16 sets (of 2) nails wrapped with copper wire 1 nail has 50 coils and the other 10 coils 16 cases Iron fillings (white paper glued beneath for better visibility) 16 paper clips attached to each other 16 bags of 10 paper clips 16 circuit boards with: 4 # 2 snaps 1 # 1snap 1 # 3 snaps 1 electromagnet 1 switch 1 red and 1 black lead 1 voltmeter/ammeter 1 motor 1 magnet 1 red spinner (blade) 1 iron rod and grommet 16 simple motors 16 Transparent generators Observation sheet Divide class into 16 pairs. I. Introduction Learning Goals: Students understand the main ideas about magnets and electromagnets. A. What is a Magnet? Ask students to tell you what they know about magnets. Make sure the following information is included: All magnets have the same properties: All magnets have 2 magnetic poles.