Permanent Magnet Design Guidelines
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The Lorentz Force
CLASSICAL CONCEPT REVIEW 14 The Lorentz Force We can find empirically that a particle with mass m and electric charge q in an elec- tric field E experiences a force FE given by FE = q E LF-1 It is apparent from Equation LF-1 that, if q is a positive charge (e.g., a proton), FE is parallel to, that is, in the direction of E and if q is a negative charge (e.g., an electron), FE is antiparallel to, that is, opposite to the direction of E (see Figure LF-1). A posi- tive charge moving parallel to E or a negative charge moving antiparallel to E is, in the absence of other forces of significance, accelerated according to Newton’s second law: q F q E m a a E LF-2 E = = 1 = m Equation LF-2 is, of course, not relativistically correct. The relativistically correct force is given by d g mu u2 -3 2 du u2 -3 2 FE = q E = = m 1 - = m 1 - a LF-3 dt c2 > dt c2 > 1 2 a b a b 3 Classically, for example, suppose a proton initially moving at v0 = 10 m s enters a region of uniform electric field of magnitude E = 500 V m antiparallel to the direction of E (see Figure LF-2a). How far does it travel before coming (instanta> - neously) to rest? From Equation LF-2 the acceleration slowing the proton> is q 1.60 * 10-19 C 500 V m a = - E = - = -4.79 * 1010 m s2 m 1.67 * 10-27 kg 1 2 1 > 2 E > The distance Dx traveled by the proton until it comes to rest with vf 0 is given by FE • –q +q • FE 2 2 3 2 vf - v0 0 - 10 m s Dx = = 2a 2 4.79 1010 m s2 - 1* > 2 1 > 2 Dx 1.04 10-5 m 1.04 10-3 cm Ϸ 0.01 mm = * = * LF-1 A positively charged particle in an electric field experiences a If the same proton is injected into the field perpendicular to E (or at some angle force in the direction of the field. -
Chapter 22 Magnetism
Chapter 22 Magnetism 22.1 The Magnetic Field 22.2 The Magnetic Force on Moving Charges 22.3 The Motion of Charged particles in a Magnetic Field 22.4 The Magnetic Force Exerted on a Current- Carrying Wire 22.5 Loops of Current and Magnetic Torque 22.6 Electric Current, Magnetic Fields, and Ampere’s Law Magnetism – Is this a new force? Bar magnets (compass needle) align themselves in a north-south direction. Poles: Unlike poles attract, like poles repel Magnet has NO effect on an electroscope and is not influenced by gravity Magnets attract only some objects (iron, nickel etc) No magnets ever repel non magnets Magnets have no effect on things like copper or brass Cut a bar magnet-you get two smaller magnets (no magnetic monopoles) Earth is like a huge bar magnet Figure 22–1 The force between two bar magnets (a) Opposite poles attract each other. (b) The force between like poles is repulsive. Figure 22–2 Magnets always have two poles When a bar magnet is broken in half two new poles appear. Each half has both a north pole and a south pole, just like any other bar magnet. Figure 22–4 Magnetic field lines for a bar magnet The field lines are closely spaced near the poles, where the magnetic field B is most intense. In addition, the lines form closed loops that leave at the north pole of the magnet and enter at the south pole. Magnetic Field Lines If a compass is placed in a magnetic field the needle lines up with the field. -
Permanent Magnet DC Motors Catalog
Catalog DC05EN Permanent Magnet DC Motors Drives DirectPower Series DA-Series DirectPower Plus Series SC-Series PRO Series www.electrocraft.com www.electrocraft.com For over 60 years, ElectroCraft has been helping engineers translate innovative ideas into reality – one reliable motor at a time. As a global specialist in custom motor and motion technology, we provide the engineering capabilities and worldwide resources you need to succeed. This guide has been developed as a quick reference tool for ElectroCraft products. It is not intended to replace technical documentation or proper use of standards and codes in installation of product. Because of the variety of uses for the products described in this publication, those responsible for the application and use of this product must satisfy themselves that all necessary steps have been taken to ensure that each application and use meets all performance and safety requirements, including all applicable laws, regulations, codes and standards. Reproduction of the contents of this copyrighted publication, in whole or in part without written permission of ElectroCraft is prohibited. Designed by stilbruch · www.stilbruch.me ElectroCraft DirectPower™, DirectPower™ Plus, DA-Series, SC-Series & PRO Series Drives 2 Table of Contents Typical Applications . 3 Which PMDC Motor . 5 PMDC Drive Product Matrix . .6 DirectPower Series . 7 DP20 . 7 DP25 . 9 DP DP30 . 11 DirectPower Plus Series . 13 DPP240 . 13 DPP640 . 15 DPP DPP680 . 17 DPP700 . 19 DPP720 . 21 DA-Series. 23 DA43 . 23 DA DA47 . 25 SC-Series . .27 SCA-L . .27 SCA-S . .29 SC SCA-SS . 31 PRO Series . 33 PRO-A04V36 . 35 PRO-A08V48 . 37 PRO PRO-A10V80 . -
Equivalence of Current–Carrying Coils and Magnets; Magnetic Dipoles; - Law of Attraction and Repulsion, Definition of the Ampere
GEOPHYSICS (08/430/0012) THE EARTH'S MAGNETIC FIELD OUTLINE Magnetism Magnetic forces: - equivalence of current–carrying coils and magnets; magnetic dipoles; - law of attraction and repulsion, definition of the ampere. Magnetic fields: - magnetic fields from electrical currents and magnets; magnetic induction B and lines of magnetic induction. The geomagnetic field The magnetic elements: (N, E, V) vector components; declination (azimuth) and inclination (dip). The external field: diurnal variations, ionospheric currents, magnetic storms, sunspot activity. The internal field: the dipole and non–dipole fields, secular variations, the geocentric axial dipole hypothesis, geomagnetic reversals, seabed magnetic anomalies, The dynamo model Reasons against an origin in the crust or mantle and reasons suggesting an origin in the fluid outer core. Magnetohydrodynamic dynamo models: motion and eddy currents in the fluid core, mechanical analogues. Background reading: Fowler §3.1 & 7.9.2, Lowrie §5.2 & 5.4 GEOPHYSICS (08/430/0012) MAGNETIC FORCES Magnetic forces are forces associated with the motion of electric charges, either as electric currents in conductors or, in the case of magnetic materials, as the orbital and spin motions of electrons in atoms. Although the concept of a magnetic pole is sometimes useful, it is diácult to relate precisely to observation; for example, all attempts to find a magnetic monopole have failed, and the model of permanent magnets as magnetic dipoles with north and south poles is not particularly accurate. Consequently moving charges are normally regarded as fundamental in magnetism. Basic observations 1. Permanent magnets A magnet attracts iron and steel, the attraction being most marked close to its ends. -
Electric and Magnetic Fields the Facts
PRODUCED BY ENERGY NETWORKS ASSOCIATION - JANUARY 2012 electric and magnetic fields the facts Electricity plays a central role in the quality of life we now enjoy. In particular, many of the dramatic improvements in health and well-being that we benefit from today could not have happened without a reliable and affordable electricity supply. Electric and magnetic fields (EMFs) are present wherever electricity is used, in the home or from the equipment that makes up the UK electricity system. But could electricity be bad for our health? Do these fields cause cancer or any other disease? These are important and serious questions which have been investigated in depth during the past three decades. Over £300 million has been spent investigating this issue around the world. Research still continues to seek greater clarity; however, the balance of scientific evidence to date suggests that EMFs do not cause disease. This guide, produced by the UK electricity industry, summarises the background to the EMF issue, explains the research undertaken with regard to health and discusses the conclusion reached. Electric and Magnetic Fields Electric and magnetic fields (EMFs) are produced both naturally and as a result of human activity. The earth has both a magnetic field (produced by currents deep inside the molten core of the planet) and an electric field (produced by electrical activity in the atmosphere, such as thunderstorms). Wherever electricity is used there will also be electric and magnetic fields. Electric and magnetic fields This is inherent in the laws of physics - we can modify the fields to some are inherent in the laws of extent, but if we are going to use electricity, then EMFs are inevitable. -
An Inexpensive Hands-On Introduction to Permanent Magnet Direct Current Motors
AC 2011-1082: AN INEXPENSIVE HANDS-ON INTRODUCTION TO PER- MANENT MAGNET DIRECT CURRENT MOTORS Garrett M. Clayton, Villanova University Dr. Garrett M. Clayton received his BSME from Seattle University and his MSME and PhD in Mechanical Engineering from the University of Washington (Seattle). He is an Assistant Professor in Mechanical Engineering at Villanova University. His research interests focus on mechatronics, specifically modeling and control of scanning probe microscopes and unmanned vehicles. Rebecca A Stein, University of Pennsylvania Rebecca Stein is the Associate Director of Research and Educational Outreach in the School of Engi- neering and Applied Science at the University of Pennsylvania. She received her B.S. in Mechanical Engineering and Masters in Technology Management from Villanova University. Her background and work experience is in K-12 engineering education initiatives. Rebecca has spent the past 5 years involved in STEM high school programs at Villanova University and The School District of Philadelphia. Ad- ditionally, she has helped coordinate numerous robotics competitions such as BEST Robotics, FIRST LEGO League and MATE. Page 22.177.1 Page c American Society for Engineering Education, 2011 An Inexpensive Hands-on Introduction to Permanent Magnet Direct Current Motors Abstract Motors are an important curricular component in freshman and sophomore introduction to mechanical engineering (ME) courses as well as in curricula developed for high school science and robotics clubs. In order to facilitate a hands-on introduction to motors, an inexpensive permanent magnet direct current (PMDC) motor experiment has been developed that gives students an opportunity to build a PMDC motor from common office supplies along with a few inexpensive laboratory components. -
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. -
Glossary Module 1 Electric Charge
Glossary Module 1 electric charge - is a basic property of elementary particles of matter. The protons in an atom, for example, have positive charge, the electrons have negative charge, and the neutrons have zero charge. electrostatic force - is one of the most powerful and fundamental forces in the universe. It is the force a charged object exerts on another charged object. permittivity – is the ability of a substance to store electrical energy in an electric field. It is a constant of proportionality that exists between electric displacement and electric field intensity in a given medium. vector - a quantity having direction as well as magnitude. Module 2 electric field - a region around a charged particle or object within which a force would be exerted on other charged particles or objects. electric flux - is the measure of flow of the electric field through a given area. Module 3 electric potential - the work done per unit charge in moving an infinitesimal point charge from a common reference point (for example: infinity) to the given point. electric potential energy - is a potential energy (measured in joules) that results from conservative Coulomb forces and is associated with the configuration of a particular set of point charges within a defined system. Module 4 Capacitance - is a measure of the capacity of storing electric charge for a given configuration of conductors. Capacitor - is a passive two-terminal electrical component used to store electrical energy temporarily in an electric field. Dielectric - a medium or substance that transmits electric force without conduction; an insulator. Module 5 electric current - is a flow of charged particles. -
Exploring the Earth's Magnetic Field
([SORULQJWKH(DUWK·V0DJQHWLF)LHOG $Q,0$*(6DWHOOLWH*XLGHWRWKH0DJQHWRVSKHUH An IMAGE Satellite Guide to Exploring the Earth’s Magnetic Field 1 $FNQRZOHGJPHQWV Dr. James Burch IMAGE Principal Investigator Dr. William Taylor IMAGE Education and Public Outreach Raytheon ITS and NASA Goddard SFC Dr. Sten Odenwald IMAGE Education and Public Outreach Raytheon ITS and NASA Goddard SFC Ms. Annie DiMarco This resource was developed by Greenwood Elementary School the NASA Imager for Brookville, Maryland Magnetopause-to-Auroral Global Exploration (IMAGE) Ms. Susan Higley Cherry Hill Middle School Information about the IMAGE Elkton, Maryland Mission is available at: http://image.gsfc.nasa.gov Mr. Bill Pine http://pluto.space.swri.edu/IMAGE Chaffey High School Resources for teachers and Ontario, California students are available at: Mr. Tom Smith http://image.gsfc.nasa.gov/poetry Briggs-Chaney Middle School Silver Spring, Maryland Cover Artwork: Image of the Earth’s ring current observed by the IMAGE, HENA instrument. Some representative magnetic field lines are shown in white. An IMAGE Satellite Guide to Exploring the Earth’s Magnetic Field 2 &RQWHQWV Chapter 1: What is a Magnet? , *UDGH 3OD\LQJ:LWK0DJQHWLVP ,, *UDGH ([SORULQJ0DJQHWLF)LHOGV ,,, *UDGH ([SORULQJWKH(DUWKDVD0DJQHW ,9 *UDGH (OHFWULFLW\DQG0DJQHWLVP Chapter 2: Investigating Earth’s Magnetism 9 *UDGH *UDGH7KH:DQGHULQJ0DJQHWLF3ROH 9, *UDGH 3ORWWLQJ3RLQWVLQ3RODU&RRUGLQDWHV 9,, *UDGH 0HDVXULQJ'LVWDQFHVRQWKH3RODU0DS 9,,, *UDGH :DQGHULQJ3ROHVLQWKH/DVW<HDUV ,; *UDGH 7KH0DJQHWRVSKHUHDQG8V -
Vocabulary of Magnetism
TECHNotes The Vocabulary of Magnetism Symbols for key magnetic parameters continue to maximum energy point and the value of B•H at represent a challenge: they are changing and vary this point is the maximum energy product. (You by author, country and company. Here are a few may have noticed that typing the parentheses equivalent symbols for selected parameters. for (BH)MAX conveniently avoids autocorrecting Subscripts in symbols are often ignored so as to the two sequential capital letters). Units of simplify writing and typing. The subscripted letters maximum energy product are kilojoules per are sometimes capital letters to be more legible. In cubic meter, kJ/m3 (SI) and megagauss•oersted, ASTM documents, symbols are italicized. According MGOe (cgs). to NIST’s guide for the use of SI, symbols are not italicized. IEC uses italics for the main part of the • µr = µrec = µ(rec) = recoil permeability is symbol, but not for the subscripts. I have not used measured on the normal curve. It has also been italics in the following definitions. For additional called relative recoil permeability. When information the reader is directed to ASTM A340[11] referring to the corresponding slope on the and the NIST Guide to the use of SI[12]. Be sure to intrinsic curve it is called the intrinsic recoil read the latest edition of ASTM A340 as it is permeability. In the cgs-Gaussian system where undergoing continual updating to be made 1 gauss equals 1 oersted, the intrinsic recoil consistent with industry, NIST and IEC usage. equals the normal recoil minus 1. -
22 Magnetism
CHAPTER 22 | MAGNETISM 775 22 MAGNETISM Figure 22.1 The magnificent spectacle of the Aurora Borealis, or northern lights, glows in the northern sky above Bear Lake near Eielson Air Force Base, Alaska. Shaped by the Earth’s magnetic field, this light is produced by radiation spewed from solar storms. (credit: Senior Airman Joshua Strang, via Flickr) Learning Objectives 22.1. Magnets • Describe the difference between the north and south poles of a magnet. • Describe how magnetic poles interact with each other. 22.2. Ferromagnets and Electromagnets • Define ferromagnet. • Describe the role of magnetic domains in magnetization. • Explain the significance of the Curie temperature. • Describe the relationship between electricity and magnetism. 22.3. Magnetic Fields and Magnetic Field Lines • Define magnetic field and describe the magnetic field lines of various magnetic fields. 22.4. Magnetic Field Strength: Force on a Moving Charge in a Magnetic Field • Describe the effects of magnetic fields on moving charges. • Use the right hand rule 1 to determine the velocity of a charge, the direction of the magnetic field, and the direction of the magnetic force on a moving charge. • Calculate the magnetic force on a moving charge. 22.5. Force on a Moving Charge in a Magnetic Field: Examples and Applications • Describe the effects of a magnetic field on a moving charge. • Calculate the radius of curvature of the path of a charge that is moving in a magnetic field. 22.6. The Hall Effect • Describe the Hall effect. • Calculate the Hall emf across a current-carrying conductor. 22.7. Magnetic Force on a Current-Carrying Conductor • Describe the effects of a magnetic force on a current-carrying conductor. -
Physics 121 Lab 4: Measurement of the Earth's Magnetic Field
Physics 121 Lab 4: Measurement of the Earth’s Magnetic Field 1 Introduction The Earth’s magnetic field is well known and heavily studied. It also is ever present and affects any experiments in which relatively small magnetic fields are involved. In this lab, we will use our knowledge of the magnetic field created by currents to measure the Earth’s magnetic field in our lab. At a given location on the Earth’s surface in the northern hemisphere, the direction of the earth’s magnetic field is generally toward the earth’s north magnetic pole, but directed downward at an angle θ (called the "dip angle") below the horizontal. As shown in Figure 1 the total B field vector is related to the horizontal component BH and the dip angle by B B = H . cos θ (1) B H North θ B Figure 1: The relationship between the earth’s magnetic field B and the horizontal component BH at the earth’s surface in the northern hemisphere. 2 Apparatus We will measure the strength of the horizontal component of the earth’s magnetic field using a simple device called a tangent galvanometer. This device consists of a small magnetic compass at the center of a circular coil of wire. A power supply provides an electric current that produces a magnetic field at the center of the coil where the compass is located. The B field of the current is directed perpendicular to the plane of the coil and , as explained in class, its magnitude is given by μ 2πNI B = 0 coil 4π R (2) where N is the number of turns of wire in the coil, I is the conventional current, and R is the radius of the coil.