Key Contents. Magnetic fields and the Lorentz force. Magnetic force on current. Ampere s law. The Hall effect
|
|
- Darrell Lane
- 5 years ago
- Views:
Transcription
1 Magnetic Fields
2 Key Contents Magnetic fields and the Lorentz force The Hall effect Magnetic force on current The magnetic dipole moment Biot-Savart law Ampere s law The magnetic dipole field
3 What is a Magnetic Field? As we have discussed, one major goal of physics is the study of how an electric field can produce an electric force on a charged object; A closely related goal is the study of how a megnetic field can produce a magnetic force on a moving charged particle or on a magnetic object such as a magnet; A magnetic field is the magnetic effect of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude (or strength); as such it is a vector field.
4 What Produces a Magnetic Field Because an electric field E is produced by an electric charge, we might reasonably expect that a a magnetic field B is produced by a magnetic charge; Although individual magnetic charges (called magnetic monopoles) are predicted by certain theories, their existence has not been confirmed. How then are magnetic fields produced? There are two ways
5 What Produces a Magnetic Field? A magnetic field is generated when electric charge carriers such as electrons move through space or within an electrical conductor. The geometric shapes of the magnetic flux lines produced by moving charge carriers (electric current) are similar to the shapes of the flux lines in an electrostatic field. But there are differences in the ways electrostatic and magnetic fields interact with the environment. In everyday life, magnetic fields are most often encountered as a force created by permanent magnets, which pull on ferromagnetic materials such as iron, cobalt, or nickel, and attract or repel other magnets. Magnetic fields are widely used throughout modern technology, particularly in electrical engineering and electromechanics. The Earth produces its own magnetic field, which is important in navigation, and it shields the Earth's atmosphere from solar wind. Rotating magnetic fields are used in both electric motors and generators. Magnetic forces give information about the charge carriers in a material through the Hall effect. The interaction of magnetic fields in electric devices such as transformers is studied in the discipline of magnetic circuits.
6 The definition of B How can we define a magnetic field if there is no such thing as a magnetic charge? We must define B in another way in terms of the magnetic force F B exerted on a moving electrically charged test particle. The magnetic force on a charged particle, F B, is found to be: Here q is the charge of the particle, v is its velocity, and B the magnetic field in the region. The magnitude of this force is then: Here f is the angle between vectors v and B. # The Lorentz force: F = q(e+ v B)
7 The definition of B The SI unit for B is newton per coulomb-meter per second. For convenience, this is called the tesla (T): An earlier (non-si) unit for B is the gauss (G), and
8 The Lorentz Force F q v B
9 Magnetic Field Lines
10 Example, Magnetic Force on a Moving Charged Particle
11 Crossed Fields, Discovery of an Electron When the two fields in Fig are adjusted so that the two deflecting forces acting on the charged particle cancel, we have Thus, the crossed fields allow us to measure the speed of the charged particles passing through them. The deflection of a charged particle, moving through an electric field E without B, between two plates, at the far end of the plates is (s= v 0 t at 2 ) Here, v is the particle s speed, m its mass, q its charge, and L is the length of the plates.
12 Crossed Fields, The Hall Effect Fig A strip of copper carrying a current i is immersed in a magnetic field. (a)the situation immediately after the magnetic field is turned on. The curved path that will then be taken by an electron is shown. (b) The situation at equilibrium, which quickly follows. Note that negative charges pile up on the right side of the strip, leaving uncompensated positive charges on the left. Thus, the left side is at a higher potential than the right side. (c) For the same current direction, if the charge carriers were positively charged, they would pile up on the right side, and the right side would be at the higher potential.
13 Crossed Fields, The Hall Effect A Hall potential difference V is associated with the electric field across strip width d, and the magnitude of that potential difference is V =Ed. When the electric and magnetic forces are in balance (Fig. 28-8b), where v d is the drift speed. But, Where J is the current density, A the cross-sectional area, e the electronic charge, and n the number of charges per unit volume. Therefore, n d V i A B e Here, l=( A/d), the thickness of the strip. One may measure the number density of the charge carriers and also determine the sign (polarity) of the charge!
14 A Circulating Charged Particle Consider a particle of charge magnitude q and mass m moving perpendicular to a uniform magnetic field B, at speed v. The magnetic force continuously deflects the particle, and since B and v are always perpendicular to each other, this deflection causes the particle to follow a circular path. The magnetic force acting on the particle has a magnitude of q vb. Fig Electrons circulating in a chamber containing gas at low pressure (their path is the glowing circle). A uniform magnetic field, B, pointing directly out of the plane of the page, fills the chamber. Note the radially directed magnetic force F B ; for circular motion to occur, F B must point toward the center of the circle, (Courtesy John Le P.Webb, Sussex University, England)
15 A Circulating Charged Particle For uniform circular motion Fig Electrons circulating in a chamber containing gas at low pressure (their path is the glowing circle). A uniform magnetic field, B, pointing directly out of the plane of the page, fills the chamber. Note the radially directed magnetic force F B ; for circular motion to occur, F B must point toward the center of the circle, (Courtesy John Le P.Webb, Sussex University, England)
16 Helical Paths The velocity vector, v, of such a particle resolved into two components, one parallel to and one perpendicular to it: The parallel component determines the pitch p of the helix (the distance between adjacent turns (Fig b)). The perpendicular component determines the radius of the helix. The more closely spaced field lines at the left and right sides indicate that the magnetic field is stronger there. When the field at an end is strong enough, the particle reflects from that end. If the particle reflects from both ends, it is said to be trapped in a magnetic bottle or magnetic mirror.
17 Example Helical Motion of a Charged Particle in a Magnetic Field
18 Example, Uniform Circular Motion of a Charged Particle in a Magnetic Field
19 Magnetic Force on a Current-Carrying Wire
20 Magnetic Force on a Current-Carrying Wire
21 Example, Magnetic Force on a Wire Carrying Current
22 Torque on a Current Loop The figure shows a simple motor consisting of a single curent-carrying loop immersed in a magnetic field. The two magnetic forces produce a torque on the loop tending to rotate it about its central axis.
23 Torque on a Current Loop For N loops, when A=ab, the area of the loop, the total torque is:
24 The Magnetic Dipole Moment, m Definition: Here, N is the number of turns in the coil, i is the current through the coil, and A is the area enclosed by each turn of the coil. Direction: The direction of m is that of the normal vector to the plane of the coil.
25 The Magnetic Dipole Moment, m The definition of torque can be rewritten as: Just as in the electric case, the magnetic dipole in an external magnetic field has an energy that depends on the dipole s orientation in the field: A magnetic dipole has its lowest energy (-mb cos 0=mB) when its dipole moment m is lined up with the magnetic field. It has its highest energy (-mb cos 180 =+mb) when m is directed opposite the field.
26 Calculating the Magnetic Field due to a Current Symbol m 0 is a constant, called the permeability constant, whose value is In vector form
27 Magnetic Field due to a Long Straight Wire The magnitude of the magnetic field at a perpendicular distance R from a long (infinite) straight wire carrying a current i is given by Fig Iron filings that have been sprinkled onto cardboard collect in concentric circles when current is sent through the central wire. The alignment, which is along magnetic field lines, is caused by the magnetic field produced by the current. (Courtesy Education Development Center)
28 Magnetic Field due to a Long Straight Wire
29 Magnetic Field due to a Current in a Circular Arc of Wire
30 Example, Magnetic field at the center of a circular arc of a circle
31 Example, Magnetic field off to the side of two long straight currents
32 Force Between Two Parallel Wires
33 Ampere s Law Curl your right hand around the Amperian loop, with the fingers pointing in the direction of integration. A current through the loop in the general direction of your outstretched thumb is assigned a plus sign, and a current generally in the opposite direction is assigned a minus sign.
34 Ampere s Law Magnetic Field Outside a Long Straight Wire Carrying Current
35 Ampere s Law Magnetic Field Inside a Long Straight Wire Carrying Current
36 Example Ampere s Law to find the magnetic field inside a long cylinder of current.
37 Solenoids and Toroids Fig A vertical cross section through the central axis of a stretched-out solenoid. The back portions of five turns are shown, as are the magnetic field lines due to a current through the solenoid. Each turn produces circular magnetic field lines near itself. Near the solenoid s axis, the field lines combine into a net magnetic field that is directed along the axis. The closely spaced field lines there indicate a strong magnetic field. Outside the solenoid the field lines are widely spaced; the field there is very weak.
38 Solenoids Fig Application of Ampere s law to a section of a long ideal solenoid carrying a current i. The Amperian loop is the rectangle abcda. Here n be the number of turns per unit length of the solenoid
39 Magnetic Field of a Toroid where i is the current in the toroid windings (and is positive for those windings enclosed by the Amperian loop) and N is the total number of turns. This gives
40 Example, The field inside a solenoid
41 A Current Carrying Coil as a Magnetic Dipole
42 A Current Carrying Coil as a Magnetic Dipole
Chapter 29. Magnetic Fields due to Currentss
Chapter 29 Magnetic Fields due to Currentss Refresher: The Magnetic Field Permanent bar magnets have opposite poles on each end, called north and south. Like poles repel; opposites attract. If a magnet
More informationChapter 28. Magnetic Fields. Copyright 2014 John Wiley & Sons, Inc. All rights reserved.
Chapter 28 Magnetic Fields Copyright 28-2 What Produces a Magnetic Field? 1. Moving electrically charged particles ex: current in a wire makes an electromagnet. The current produces a magnetic field that
More information10/24/2012 PHY 102. (FAWOLE O.G.) Good day. Here we go..
Good day. Here we go.. 1 PHY102- GENERAL PHYSICS II Text Book: Fundamentals of Physics Authors: Halliday, Resnick & Walker Edition: 8 th Extended Lecture Schedule TOPICS: Dates Ch. 28 Magnetic Fields 12
More informationMagnetic Fields due to Currents
Observation: a current of moving charged particles produces a magnetic field around the current. Chapter 29 Magnetic Fields due to Currents Magnetic field due to a current in a long straight wire a current
More informationHandout 8: Sources of magnetic field. Magnetic field of moving charge
1 Handout 8: Sources of magnetic field Magnetic field of moving charge Moving charge creates magnetic field around it. In Fig. 1, charge q is moving at constant velocity v. The magnetic field at point
More informationPhysics 202, Lecture 13. Today s Topics. Magnetic Forces: Hall Effect (Ch. 27.8)
Physics 202, Lecture 13 Today s Topics Magnetic Forces: Hall Effect (Ch. 27.8) Sources of the Magnetic Field (Ch. 28) B field of infinite wire Force between parallel wires Biot-Savart Law Examples: ring,
More informationCHETTINAD COLLEGE OF ENGINEERING & TECHNOLOGY NH-67, TRICHY MAIN ROAD, PULIYUR, C.F , KARUR DT.
CHETTINAD COLLEGE OF ENGINEERING & TECHNOLOGY NH-67, TRICHY MAIN ROAD, PULIYUR, C.F. 639 114, KARUR DT. DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING COURSE MATERIAL Subject Name: Electromagnetic
More informationChapter 21. Magnetism
Chapter 21 Magnetism Magnets Poles of a magnet are the ends where objects are most strongly attracted Two poles, called north and south Like poles repel each other and unlike poles attract each other Similar
More informationAmpere s law. Lecture 15. Chapter 32. Physics II. Course website:
Lecture 15 Chapter 32 Physics II Ampere s law Course website: http://faculty.uml.edu/andriy_danylov/teaching/physicsii Ampere s Law Electric Field From Coulomb s law 1 4 Magnetic Field Bio-Savart law 4
More informationCHAPTER 20 Magnetism
CHAPTER 20 Magnetism Units Magnets and Magnetic Fields Electric Currents Produce Magnetic Fields Force on an Electric Current in a Magnetic Field; Definition of B Force on Electric Charge Moving in a Magnetic
More informationChapter 22, Magnetism. Magnets
Chapter 22, Magnetism Magnets Poles of a magnet (north and south ) are the ends where objects are most strongly attracted. Like poles repel each other and unlike poles attract each other Magnetic poles
More informationMagnetic Fields and Forces
Nicholas J. Giordano www.cengage.com/physics/giordano Chapter 20 Magnetic Fields and Forces Marilyn Akins, PhD Broome Community College Magnetism Magnetic fields are produced by moving electric charges
More informationChapter 21. Magnetic Forces and Magnetic Fields
Chapter 21 Magnetic Forces and Magnetic Fields 21.1 Magnetic Fields The needle of a compass is permanent magnet that has a north magnetic pole (N) at one end and a south magnetic pole (S) at the other.
More informationMarch 11. Physics 272. Spring Prof. Philip von Doetinchem
Physics 272 March 11 Spring 2014 http://www.phys.hawaii.edu/~philipvd/pvd_14_spring_272_uhm.html Prof. Philip von Doetinchem philipvd@hawaii.edu Phys272 - Spring 14 - von Doetinchem - 32 Summary Magnetic
More informationChapter 30. Sources of the Magnetic Field Amperes and Biot-Savart Laws
Chapter 30 Sources of the Magnetic Field Amperes and Biot-Savart Laws F B on a Charge Moving in a Magnetic Field Magnitude proportional to charge and speed of the particle Direction depends on the velocity
More informationKirchhoff s rules, example
Kirchhoff s rules, example Magnets and Magnetism Poles of a magnet are the ends where objects are most strongly attracted. Two poles, called north and south Like poles repel each other and unlike poles
More informationTorque on a Current Loop
Today Chapter 19 Magnetism Torque on a current loop, electrical motor Magnetic field around a current carrying wire. Ampere s law Solenoid Material magnetism Clicker 1 Which of the following is wrong?
More informationLecture #4.4 Magnetic Field
Lecture #4.4 Magnetic Field During last several lectures we have been discussing electromagnetic phenomena. However, we only considered examples of electric forces and fields. We first talked about electrostatics
More informationChapter 17: Magnetism
Chapter 17: Magnetism Section 17.1: The Magnetic Interaction Things You Already Know Magnets can attract or repel Magnets stick to some things, but not all things Magnets are dipoles: north and south Labels
More informationChapter 19. Magnetism
Chapter 19 Magnetism The figure shows the path of a negatively charged particle in a region of a uniform magnetic field. Answer the following questions about this situation (in each case, we revert back
More informationChapter 28. Magnetic Fields. Copyright 2014 John Wiley & Sons, Inc. All rights reserved.
Chapter 28 Magnetic Fields Copyright 28-1 Magnetic Fields and the Definition of B The Definition of B The Field. We can define a magnetic field B to be a vector quantity that exists when it exerts a force
More informationEvery magnet has a north pole and south pole.
Magnets - Intro The lodestone is a naturally occurring mineral called magnetite. It was found to attract certain pieces of metal. o one knew why. ome early Greek philosophers thought the lodestone had
More informationChapter 30 Sources of the magnetic field
Chapter 30 Sources of the magnetic field Force Equation Point Object Force Point Object Field Differential Field Is db radial? Does db have 1/r2 dependence? Biot-Savart Law Set-Up The magnetic field is
More informationChapter 28 Magnetic Fields Sources
Chapter 28 Magnetic Fields Sources All known magnetic sources are due to magnetic dipoles and inherently macroscopic current sources or microscopic spins and magnetic moments Goals for Chapter 28 Study
More informationMagnetic Forces and Fields (Chapters 29-30)
Magnetic Forces and Fields (Chapters 29-30) Magnetism Magnetic Materials and Sources Magnetic Field, Magnetic Force Force on Moving Electric Charges Lorentz Force Force on Current Carrying Wires Applications
More informationLECTURE 22 MAGNETIC TORQUE & MAGNETIC FIELDS. Instructor: Kazumi Tolich
LECTURE 22 MAGNETIC TORQUE & MAGNETIC FIELDS Instructor: Kazumi Tolich Lecture 22 2! Reading chapter 22.5 to 22.7! Magnetic torque on current loops! Magnetic field due to current! Ampere s law! Current
More informationTridib s Physics Tutorials. NCERT-XII / Unit- 4 Moving charge and magnetic field
MAGNETIC FIELD DUE TO A CURRENT ELEMENT The relation between current and the magnetic field, produced by it is magnetic effect of currents. The magnetic fields that we know are due to currents or moving
More informationLorentz Force. Velocity Selector
Lecture 9-1 Lorentz Force Let E and denote the electric and magnetic vector fields. The force F acting on a point charge q, moving with velocity v in the superimosed E fields is: F qe v This is called
More informationB for a Long, Straight Conductor, Special Case. If the conductor is an infinitely long, straight wire, θ 1 = 0 and θ 2 = π The field becomes
B for a Long, Straight Conductor, Special Case If the conductor is an infinitely long, straight wire, θ 1 = 0 and θ 2 = π The field becomes μ I B = o 2πa B for a Curved Wire Segment Find the field at point
More informationMagnetic field and magnetic poles
Magnetic field and magnetic poles Magnetic Field B is analogically similar to Electric Field E Electric charges (+ and -)are in analogy to magnetic poles(north:n and South:S). Paramagnetism, Diamagnetism,
More informationGeneral Physics II. Magnetism
General Physics II Magnetism Bar magnet... two poles: N and S Like poles repel; Unlike poles attract. Bar Magnet Magnetic Field lines [B]: (defined in a similar way as electric field lines, direction and
More informationMagnetic Forces and Fields (Chapters 32)
Magnetic Forces and Fields (Chapters 32) Magnetism Magnetic Materials and Sources Magnetic Field, B Magnetic Force Force on Moving Electric Charges Lorentz Force Force on Current Carrying Wires Applications
More informationDAY 12. Summary of Topics Covered in Today s Lecture. Magnetic Fields Exert Torques on a Loop of Current
DAY 12 Summary of Topics Covered in Today s Lecture Magnetic Fields Exert Torques on a Loop of Current Imagine a wire bent into the shape of a rectangle with height h and width w. The wire carries a current
More informationMagnetic Field Lines for a Loop
Magnetic Field Lines for a Loop Figure (a) shows the magnetic field lines surrounding a current loop Figure (b) shows the field lines in the iron filings Figure (c) compares the field lines to that of
More informationLecture 26: WED 18 MAR
Physics 2113 Aurora Borealis Jonathan Dowling Lecture 26: WED 18 MAR Magnetic fields I ll be back. The Hall Effect Charge Flow in Conductors is From Electrons: Benjamin Franklin s Biggest Blunder! 28.5:
More informationMagnetic Fields Permanent Magnets
1 Magnetic Fields Permanent Magnets Magnetic fields are continuous loops leaving a North pole and entering a South pole they point in direction that an isolated North would move Highest strength near poles
More informationMay 08, Magnetism.notebook. Unit 9 Magnetism. This end points to the North; call it "NORTH." This end points to the South; call it "SOUTH.
Unit 9 Magnetism This end points to the North; call it "NORTH." This end points to the South; call it "SOUTH." 1 The behavior of magnetic poles is similar to that of like and unlike electric charges. Law
More informationProblem Fig
Problem 27.15 An electron at point A has a speed of 1.41 x 10 6 m/s. Find (a) the magnitude and direction of the magnetic field that will cause the electron to follow the semicircular path from A to B,
More informationPHYS152 Lecture 8. Eunil Won Korea University. Ch 30 Magnetic Fields Due to Currents. Fundamentals of Physics by Eunil Won, Korea University
PHYS152 Lecture 8 Ch 3 Magnetic Fields Due to Currents Eunil Won Korea University Calculating the Magnetic Field Due to a Current Recall that we had the formula for the electrostatic force: d E = 1 ɛ dq
More informationPhysics H. Instructor: Dr. Alaa Mahmoud
Physics 202 1436-1437 H Instructor: Dr. Alaa Mahmoud E-mail: alaa_y_emam@hotmail.com Chapter 28 magnetic Field Magnetic fingerprinting allows fingerprints to be seen on surfaces that otherwise would not
More informationINTRODUCTION MAGNETIC FIELD OF A MOVING POINT CHARGE. Introduction. Magnetic field due to a moving point charge. Units.
Chapter 9 THE MAGNETC FELD ntroduction Magnetic field due to a moving point charge Units Biot-Savart Law Gauss s Law for magnetism Ampère s Law Maxwell s equations for statics Summary NTRODUCTON Last lecture
More informationPHYSICS. Chapter 29 Lecture FOR SCIENTISTS AND ENGINEERS A STRATEGIC APPROACH 4/E RANDALL D. KNIGHT
PHYSICS FOR SCIENTISTS AND ENGINEERS A STRATEGIC APPROACH 4/E Chapter 29 Lecture RANDALL D. KNIGHT Chapter 29 The Magnetic Field IN THIS CHAPTER, you will learn about magnetism and the magnetic field.
More informationMagnetostatics: Part 1
Magnetostatics: Part 1 We present magnetostatics in comparison with electrostatics. Sources of the fields: Electric field E: Coulomb s law. Magnetic field B: Biot-Savart law. Charge Current (moving charge)
More informationChapter 22 Magnetism
Chapter 22 Magnetism 1 Overview of Chapter 22 The Magnetic Field The Magnetic Force on Moving Charges The Motion of Charged Particles in a Magnetic Field The Magnetic Force Exerted on a Current-Carrying
More informationPhysics 1402: Lecture 17 Today s Agenda
Physics 1402: Lecture 17 Today s Agenda Announcements: Midterm 1 distributed today Homework 05 due Friday Magnetism Trajectory in Constant B Field Suppose charge q enters B field with velocity v as shown
More informationMagnetic Fields. or I in the filed. ! F = q! E. ! F = q! v! B. q! v. Charge q as source. Current I as source. Gauss s Law. Ampere s Law.
Magnetic Fields Charge q as source Gauss s Law Electric field E F = q E Faraday s Law Ampere-Maxwell Law Current I as source Magnetic field B Ampere s Law F = q v B Force on q in the field Force on q v
More informationMODULE 4.2 MAGNETISM ELECTRIC CURRENTS AND MAGNETISIM VISUAL PHYSICS ONLINE
VISUAL PHYSICS ONLINE MODULE 4.2 MAGNETISM ELECTRIC CURRENTS AND MAGNETISIM When electric charges are in motion they exert forces on each other that can t be explained by Coulomb s law. If two parallel
More informationPhysics 12. Unit 8 Magnetic Field and Electromagnetism Part I
Physics 12 Unit 8 Magnetic Field and Electromagnetism Part I 1. Basics about magnets Magnets have been known by ancient people since long time ago, referring to the iron-rich rocks, called magnetite or
More informationModule 3: Electromagnetism
Module 3: Electromagnetism Lecture - Magnetic Field Objectives In this lecture you will learn the following Electric current is the source of magnetic field. When a charged particle is placed in an electromagnetic
More informationPhysics / Higher Physics 1A. Electricity and Magnetism Revision
Physics / Higher Physics 1A Electricity and Magnetism Revision Electric Charges Two kinds of electric charges Called positive and negative Like charges repel Unlike charges attract Coulomb s Law In vector
More informationMAGNETIC PROBLEMS. (d) Sketch B as a function of d clearly showing the value for maximum value of B.
PHYS2012/2912 MAGNETC PROBLEMS M014 You can investigate the behaviour of a toroidal (dough nut shape) electromagnet by changing the core material (magnetic susceptibility m ) and the length d of the air
More informationElectrics. Electromagnetism
Electrics Electromagnetism Electromagnetism Magnetism is associated with charges in motion (currents): microscopic currents in the atoms of magnetic materials. macroscopic currents in the windings of an
More information6.3 Magnetic Force and Field (4 hr)
6.3 Magnetic Force and Field (4 hr) Name Activity 631 Investigating Magnetic Field around a magnet Activity 632 Investigating Electric Field in a slinky. Activity 633 Build your own Electric Motor. Read
More informationCalculus Relationships in AP Physics C: Electricity and Magnetism
C: Electricity This chapter focuses on some of the quantitative skills that are important in your C: Mechanics course. These are not all of the skills that you will learn, practice, and apply during the
More informationMagnetic Fields Part 2: Sources of Magnetic Fields
Magnetic Fields Part 2: Sources of Magnetic Fields Last modified: 08/01/2018 Contents Links What Causes a Magnetic Field? Moving Charges Right Hand Grip Rule Permanent Magnets Biot-Savart Law Magnetic
More informationThe Steady Magnetic Field LECTURE 7
The Steady Magnetic Field LECTURE 7 Learning Objectives Understand the Biot-Savart Law Understand the Ampere s Circuital Law Explain the Application of Ampere s Law Motivating the Magnetic Field Concept:
More informationChapter 5. Magnetostatics
Chapter 5. Magnetostatics 5.1 The Lorentz Force Law 5.1.1 Magnetic Fields Consider the forces between charges in motion Attraction of parallel currents and Repulsion of antiparallel ones: How do you explain
More informationGravity Electromagnetism Weak Strong
19. Magnetism 19.1. Magnets 19.1.1. Considering the typical bar magnet we can investigate the notion of poles and how they apply to magnets. 19.1.1.1. Every magnet has two distinct poles. 19.1.1.1.1. N
More informationMagnetostatics III. P.Ravindran, PHY041: Electricity & Magnetism 1 January 2013: Magntostatics
Magnetostatics III Magnetization All magnetic phenomena are due to motion of the electric charges present in that material. A piece of magnetic material on an atomic scale have tiny currents due to electrons
More informationMagnetic Forces and Fields
Magnetic Forces and Fields Physics 102 Lecture 3 21 February 2002 IF NOT REGISTERED FOR PHYSICS 102, SEE REGISTRAR ASAP, AND REGISTER 21 Feb 2002 Physics 102 Lecture 3 1 RC Puzzler 21 Feb 2002 Physics
More informationSources of Magnetic Field
Chapter 28 Sources of Magnetic Field PowerPoint Lectures for University Physics, 14th Edition Hugh D. Young and Roger A. Freedman Lectures by Jason Harlow Learning Goals for Chapter 28 Looking forward
More information1-1 Magnetism. q ν B.(1) = q ( ) (2)
1-1 Magnetism Magnets exert forces on each other just like charges. You can draw magnetic field lines just like you drew electric field lines. Magnetic north and south pole s behavior is not unlike electric
More informationμ 0 I enclosed = B ds
Ampere s law To determine the magnetic field created by a current, an equation much easier to use than Biot-Savart is known as Ampere s law. As before, μ 0 is the permeability of free space, 4π x 10-7
More informationMagnetic field creation (example of a problem)
1 Magnetic field creation (example of a problem) Three long, straight wires are parallel to each other and perpendicular to the plane of the paper. Their mutual location is shown in Figure below. The currents
More informationChapter 19. Magnetism
Chapter 19 Magnetism Magnetic Fields and Forces Fundamentally they do not exist If we had special relativity we would find there is no such thing as a magnetic field. It is only a relativistic transformation
More informationLecture Outlines Chapter 22. Physics, 3 rd Edition James S. Walker
Lecture Outlines Chapter 22 Physics, 3 rd Edition James S. Walker 2007 Pearson Prentice Hall This work is protected by United States copyright laws and is provided solely for the use of instructors in
More informationMOVING CHARGES AND MAGNETISM
4 MOVING CHARGES AND MAGNETISM Moving charges can produce magnetic field. Magnetic field is produced around current carrying conductors also. The SI unit of magnetic induction (magnetic field intensity
More informationElements of Physics II. Agenda for Today. Physics 201: Lecture 1, Pg 1
Forces on currents Physics 132: Lecture e 19 Elements of Physics II Agenda for Today Currents are moving charges Torque on current loop Torque on rotated loop Currents create B-fields Adding magnetic fields
More information1. Write the relation for the force acting on a charge carrier q moving with velocity through a magnetic field in vector notation. Using this relation, deduce the conditions under which this force will
More informationCurrent in a Magnetic Field Learning Outcomes. Force on a Current-Carrying Conductor
1 Current in a Magnetic Field Learning Outcomes Discuss the force on a current-carrying conductor in a magnetic field. Demonstrate this force. Solve problems about this force. Discuss applications of this
More informationChapter 27 Sources of Magnetic Field
Chapter 27 Sources of Magnetic Field In this chapter we investigate the sources of magnetic of magnetic field, in particular, the magnetic field produced by moving charges (i.e., currents). Ampere s Law
More informationMagnetic Force Cyclotron motion
Lecture 15 Chapter 29 Physics II Magnetic Force Cyclotron motion Course website: http://faculty.uml.edu/andriy_danylov/teaching/physicsii Today we are going to discuss: Chapter 29: Section 29.7 (Skip the
More informationCoaxial cable. Coaxial cable. Magnetic field inside a solenoid
Divergence and circulation Surface S Ampere s Law A vector field is generally characterized by 1) how field lines possibly diverge away from or converge upon (point) sources plus 2) how field lines circulate,
More informationPhysics 202, Lecture 12. Today s Topics
Physics 202, Lecture 12 Today s Topics Magnetic orces (Ch. 27) Review: magnetic force, magnetic dipoles Motion of charge in uniform field: Applications: cyclotron, velocity selector, Hall effect Sources
More information1. An isolated stationary point charge produces around it. a) An electric field only. b) A magnetic field only. c) Electric as well magnetic fields.
1. An isolated stationary point charge produces around it. a) An electric field only. b) A magnetic field only. c) Electric as well magnetic fields. 2. An isolated moving point charge produces around it.
More informationAnnouncements This week:
Announcements This week: Homework due Thursday March 22: Chapter 26 sections 3-5 + Chapter 27 Recitation on Friday March 23: Chapter 27. Quiz on Friday March 23: Homework, Lectures 12, 13 and 14 Properties
More informationDr. Todd Satogata (ODU/Jefferson Lab) Wednesday, March
Vector pointing OUT of page Vector pointing IN to page University Physics 227N/232N Ch: 26-27: Magnetism and Magnetic Induction Lab this Friday, Mar 21: Ohms Law and DC RC Circuits So NO QUIZ this Friday!
More informationLecture 23: FRI 16 OCT
Aurora Borealis Physics 2113 Jonathan Dowling Lecture 23: FRI 16 OCT Magnetic Fields I I ll be back. How Do You Use Magnetic Fields in Your Everyday Life? 28.2: What Produces Magnetic Field?: One way
More informationChapter 19. Magnetism. 1. Magnets. 2. Earth s Magnetic Field. 3. Magnetic Force. 4. Magnetic Torque. 5. Motion of Charged Particles. 6.
Chapter 19 Magnetism 1. Magnets 2. Earth s Magnetic Field 3. Magnetic Force 4. Magnetic Torque 5. Motion of Charged Particles 6. Amperes Law 7. Parallel Conductors 8. Loops and Solenoids 9. Magnetic Domains
More informationChapter 28 Sources of Magnetic Field
Chapter 28 Sources of Magnetic Field In this chapter we investigate the sources of magnetic of magnetic field, in particular, the magnetic field produced by moving charges (i.e., currents). Ampere s Law
More informationIII.Sources of Magnetic Fields - Ampere s Law - solenoids
Magnetism I. Magnetic Field - units, poles - effect on charge II. Magnetic Force on Current - parallel currents, motors III.Sources of Magnetic Fields - Ampere s Law - solenoids IV.Magnetic Induction -
More informationLecture PowerPoints. Chapter 20 Physics: Principles with Applications, 6 th edition Giancoli
Lecture PowerPoints Chapter 20 Physics: Principles with Applications, 6 th edition Giancoli 2005 Pearson Prentice Hall This work is protected by United States copyright laws and is provided solely for
More informationGeneral Physics II. Magnetic Fields and Forces
General Physics II Magnetic Fields and Forces 1 Magnetism Magnetism underlies the operation of the hard disk drive, which is the mainstay of modern electronic information storage, from computers to ipods.
More informationMagnetic Force Cyclotron motion
Lecture 17 Chapter 29 Magnetic Force Cyclotron motion Messiah!? Miraculous appearance out of the blue. Course website: http://faculty.uml.edu/andriy_danylov/teaching/physicsii Today we are going to discuss:
More informationMagnets. Domain = small magnetized region of a magnetic material. all the atoms are grouped together and aligned
Magnetic Fields Magnets Domain = small magnetized region of a magnetic material all the atoms are grouped together and aligned Magnets Ferromagnetic materials domains can be forced to line up by applying
More informationCh 30 - Sources of Magnetic Field
Ch 30 - Sources of Magnetic Field Currents produce Magnetism? 1820, Hans Christian Oersted: moving charges produce a magnetic field. The direction of the field is determined using a RHR. Oersted (1820)
More informationMagnetism is associated with charges in motion (currents):
Electrics Electromagnetism Electromagnetism Magnetism is associated with charges in motion (currents): microscopic currents in the atoms of magnetic materials. macroscopic currents in the windings of an
More informationChapter 28 Sources of Magnetic Field
Chapter 28 Sources of Magnetic Field In this chapter we investigate the sources of magnetic field, in particular, the magnetic field produced by moving charges (i.e., currents), Ampere s Law is introduced
More informationMagnetic Forces and Magnetic Fields
Magnetic Forces and Magnetic Fields 21.1 Magnetic Fields The behavior of magnetic poles is similar to that of like and unlike electric charges. 21.1 Magnetic Fields The needle of a compass is permanent
More informationElectric vs Magnetic Comparison
5. MAGNETOSTATICS Electric vs Magnetic Comparison J=σE Most dielectrics µ = µo excluding ferromagnetic materials Gauss s Law E field is conservative Gauss s law (integral) Conservative E field Electric
More informationChapter 4: Magnetic Field
Chapter 4: Magnetic Field 4.1 Magnetic Field 4.1.1 Define magnetic field Magnetic field is defined as the region around a magnet where a magnetic force can be experienced. Magnetic field has two poles,
More informationA moving charge produces both electric field and magnetic field and both magnetic field can exert force on it.
Key Concepts A moving charge produces both electric field and magnetic field and both magnetic field can exert force on it. Note: In 1831, Michael Faraday discovered electromagnetic induction when he found
More informationAgenda for Today. Elements of Physics II. Forces on currents
Forces on currents Physics 132: Lecture e 19 Elements of Physics II Agenda for Today Currents are moving charges Torque on current loop Torque on rotated loop Currents create B-fields Adding magnetic fields
More informationChapter 20 Lecture Notes
Chapter 20 Lecture Notes Physics 2424 - Strauss Formulas: B = µ 0 I/2πr B = Nµ 0 I/(2R) B = µ 0 ni Σ B l = µ 0 I F = Bqv sinθ r = mv/bq m = (er 2 /2V) B 2 F = ILB sinθ τ = NIAB sinϕ F/L = I 2 I 1 µ 0 /2πd
More informationMagnetostatics. Lecture 23: Electromagnetic Theory. Professor D. K. Ghosh, Physics Department, I.I.T., Bombay
Magnetostatics Lecture 23: Electromagnetic Theory Professor D. K. Ghosh, Physics Department, I.I.T., Bombay Magnetostatics Up until now, we have been discussing electrostatics, which deals with physics
More informationThe initial magnetization curve shows the magnetic flux density that would result when an increasing magnetic field is applied to an initially
MAGNETIC CIRCUITS The study of magnetic circuits is important in the study of energy systems since the operation of key components such as transformers and rotating machines (DC machines, induction machines,
More informationHomework. Suggested exercises: 32.1, 32.3, 32.5, 32.7, 32.9, 32.11, 32.13, 32.15, 32.18, 32.20, 32.24, 32.28, 32.32, 32.33, 32.35, 32.37, 32.
Homework Reading: Chap. 32 and Chap. 33 Suggested exercises: 32.1, 32.3, 32.5, 32.7, 32.9, 32.11, 32.13, 32.15, 32.18, 32.20, 32.24, 32.28, 32.32, 32.33, 32.35, 32.37, 32.39 Problems: 32.46, 32.48, 32.52,
More informationMagnets. Magnetic vs. Electric
Magnets A force is applied to the iron filings causing them to align themselves to the direction of the magnetic field. A compass needle will tell you the direction of the field. Show Fields of little
More information(1) I have completed at least 50% of the reading and study-guide assignments associated with the lecture, as indicated on the course schedule.
iclicker Quiz (1) I have completed at least 50% of the reading and study-guide assignments associated with the lecture, as indicated on the course schedule. a) True b) False Hint: pay attention to how
More informationPhysics 202, Lecture 11
Physics 202, Lecture 11 Today s Topics Magnetic Fields and Forces (Ch. 27) Magnetic materials Magnetic forces on moving point charges Magnetic forces on currents, current loops Motion of charge in uniform
More information