Faraday s Law and Inductance
|
|
- Paula Wilkerson
- 7 years ago
- Views:
Transcription
1 Historical Overview Faraday s Law and Inductance So far studied electric fields due to stationary charges and magentic fields due to moving charges. Now study electric field due to a changing magnetic field. Faraday showed that an electric current can be induced in a circuit by a changing magnetic field. These studies lead to Faraday s law of induction. Faraday s law of induction A straight metal wire lies in a uniform magnetic field directed into the page. The wire contains free elctrons. Move the wire with a velocity v to the right. F = qv B implies that a magnetic force acts on the wire. Can use the right hand rule to show that the force on the electrons is downward, along the wire. The electrons move along the wire in response to this force: a current. Consider a loop of wire connected to a sensitive ammeter. Move a magnet toward the loop, the ammeter needle deflects in one direction. If the magnet is stationary, no current is detected. If the magnet is stationary and the coil is moved either away or toward it, a current is detected. An electric force is set up in the coil as long as relative motion occurs between the magnet and the coil. The current in the wire is called an induced current, produced by an induced electromotive force or emf. Faraday concluded that an electric current can be produced by a timevarying magnetic field. In the example above, what causes the time-varying magnetic field? Current cannot be produced by a steady magnetic field. Discuss Figure 23.3 To quantify this, define magnetic flux. 1
2 Consider an element of area da on an arbitrarily shaped open surface. If the magnetic field at the location of this element is B, the magnetic flux through the element is B.dA, where doverlinea is a vector perpendicular to the surface whose magnitude equals area da. Then the total magnetic flux through the surface is Φ B = B.A SI unit of magnetic flux is tesla-meter squared, where 1 weber or Wb = 1T.m 2. an emf is induced in a circuit when the magnetic flux through the surface bounded by the circuit changes with time. Faradays law of induction states that the emf induced in a circuit is equal to the time rate of change of magnetic flux through the circuit. ɛ = dφ B dt, where Φ B is the magnetic flux through the surface bounded by the circuit. If the circuit is a coil consisting of N identical and concentric loops and if the field lines pass through all loops, the induced emf is Why is cosθ needed here. ɛ = N dφ B ɛ = d dt (BAcosθ). Thus an emf can be induced in a circuit by changing the magnetic flux in several ways: Motional emf magnitude of B can vary with time the area A of the circuit can change with time the angle θ between B and the normal to the plane can change with time any combination of these changes Try QuickQuiz 23.1, go over example An emf is induced in a conductor moving through a magnetic field - motional emf. 2
3 Go over Figure The Alternating Current generator The alternating-current (AC) generator is a device in which energy is transferred in by work and out by electrical transmission: A coil of wire rotated in an external magnetic field by some external agent - this is the work input. For example, in a hydroelectric power plant, falling water directed against the blades of a turbine produces the rotary motion. As the loop rotates, the magnetic flux through it changes with time, inducing an emf and a current in a circuit connected to the coil. Suppose the coil has N turns of the same area A and suppose the coil rotates with a constant angular speed ω about an axis perpendicular to the magnetic field. If θ is the angle between the magnetic field and the direction perpendicular to the plane of the coil, the magnetic flux through the loop at any time t is given by: where θ = ωt. Φ B = BAcosθ = BAcosωt, Thus the induced emf in the coil is ɛ = N dφ B dt = NAB d dt (cosωt) = NABsinωt. Thus the emf varies sinusoidally with time - AC voltage. Lenz s Law Negative sign in Faraday s law. The polarity of the induced emf in a loop is such that it produces a current whose magentic field opposes the change in magnetic flux through the loop. That is the induced current is in a direction such that the induced magnetic field attempts to maintain the original flux through the loop. Go over Figure Induced emfs and Electric Fields A changing magnetic flux indices an emf and a current in a conducting loop. The current is due to an electric field setup by a battery, for example. Can also think of this as the following: a changing magnetic field creates an induced electric field. This electric field applies a force on the charges to cause them to move. 3
4 An electric field is created in a conductor as a result of changing magnetic flux - or - An electric field is always generated by a changing magnetic flux, even in free space where no charges are present. But the induced electric field has different properties to the electrostatic fields produced by stationary charges. Consider a conducting loop of radius r in a uniform magnetic field that is perpendiuclar to the plane of the loop. If the magnetic field changes with time, Faraday s law tells su that ɛ = dφ B /dt is induced in the loop. The induced current thus produced implies an induced electric field, E, that must be tangent to the loop so as to provide an electric force on the charges around the loop. The work done by the electric field on the loop in moving a test charge q once around the loop is W = qɛ. But the force on the charge is qe, and W = F.dr = qe(2πr). Equating these two expressions, we get E = ɛ 2πr. Using this result, together with faraday s law and Φ B = BA, we find E = r 2 db The negative sign indicates that the induced electric field E results in a current that opposes the change in the magnetic field. This result is valid in the absence of a conductor or charges. Thus the general form of Faraday s law of induction is ɛ = E.ds = dφ B The induced electric field E that appears above is a non-conservative field that is generated by a changing magnetic field. Its non-conservative because the work done in moving a charge around a closed path is not zero. Is this like an electrostatic filed? Self-Inductance Consider an isolated circuit consisting of a swicth, a resistor and a source of emf. 4
5 When the switch is closed, the current doesnt jump from zero to ɛ/r immediately. As the current increases with time, the magnetic flux through the loop of the circuit itself due to the current also increases with time. This increasing magnetic flux from the circuit induces an emf in the ciruit (back emf) that opposes the change in the net magnetic flux through the loop of the circuit. By Lenz s law, the induced electric field in the wires must therefore be opposite the direction of the current. the opposing emf results in a gradual increase in the emf. The emf setup in this case is called self-induced emf. From Faraday s law, the induced emf is the negative time rate of change of the magnetic flux. The magnetic flux is proportional to the magnetic field (why?), which in turn is proportional to the current in the circuit (why?). Thus the self induced emf is always proportional to the time rate of change of the current. More quantitatively, for a closely spaced coil of N turns, ɛ L = N dφ B dt = L di dt, where L is a proportionality constant called the inductance of the coil. The inductance of a coil containing N loops is L = NΦ B I. The inductance is the ratio, ɛ L L = di/ The SI unit of inductance is the henry (H): 1H = 1V.s/A. Inductance of a coil depends on geometry. A circuit that contains a coil, such as a solenoid, has a self-inductance that prevents the current from increasing or decreasing instantaneously. RL Circuits A circuit that contains a coil, such as a solenoid, has a self-inductance that prevents the current from increasing or decreasing instantaneously. A circuit element whose main purpose is to provide inductance in a circuit is called an inductor. Consider the circuit shown, consistin gof a resistor, an inductor, a swicth and a battery. 5
6 Ignore the resistance of the battery and suppose the switch is closed at t = 0. The current begins to increase, and due to the opposing current, the inductor produces an emf that opposes the increasing current. The back emf produced by the inductor is ɛ L = L di Applying Kirchoof s loop rule to the circuit: ɛ IR L di dt = 0, where IR is the voltage drop across the resistor. The potential difference across the inductor is given a negative sign because its emf is in the opposite sense to that of the battery. This is a differential equation. Its solution will give I(t). Can show the solution is I(t) = ɛ R (1 e t/τ ), where τ is the time constant of the RL circuit and τ = L/R. Dimension of τ is time. It is the time interval required for the current to reach (1 e 1 ) = of its final value ɛ/r. Note I(t) = 0 when t = 0. And at t = inf, I = ɛ/r. The final current, ɛ/r does not involve the inductance L because the inductor has no effect on the circuit if the current is not changing. Energy Stored in a Magnetic Field Induced emf set up by an inductor prevents a battery from establishing an instantaneous current. Part of the energy supplied by the batter goes into the internal energy in the resistor. The remaining energy is stored in the inductor. From Kirchoffls loop law, we have Iɛ = I 2 R + LI di This says that the rate, Iɛ, at which energy is supplied by the battery equals the rate, I 2 R, at which energy is delivered to the resistor and the rate, LI(dI/dt) at which energy is delivered to the inductor. 6
7 Thus, if U B is the energy stored in the inductor at any time, SOlving this, we get du B dt = LI di U B = 1 2 LI2, where L is constant. This is the energy stored in the magnetic field of the inductor when the current is I. Now consider a solenoid where L = µ 0 n 2 Al. The magnetic field of the solenoid is B = mu 0 ni. Then U B = 1 2 LI2 = 1 2 µ 0n 2 Al( B µ 0 n ) 2 = B2 2µ 0 (Al). Because Al is the volume of the solenoid, the energy stored per unit volume in a magnetic field, or the megnetic energy density, is u B = B2 1µ 0. This formula is valid for any region of space in which a magnetic field exists. Compare to eneergy per unit volume stored in an electric field, 1 2 ɛ 0E 2. 7
Induced voltages and Inductance Faraday s Law
Induced voltages and Inductance Faraday s Law concept #1, 4, 5, 8, 13 Problem # 1, 3, 4, 5, 6, 9, 10, 13, 15, 24, 23, 25, 31, 32a, 34, 37, 41, 43, 51, 61 Last chapter we saw that a current produces a magnetic
More informationDirection of Induced Current
Direction of Induced Current Bar magnet moves through coil Current induced in coil A S N v Reverse pole Induced current changes sign B N S v v Coil moves past fixed bar magnet Current induced in coil as
More informationInductance. Motors. Generators
Inductance Motors Generators Self-inductance Self-inductance occurs when the changing flux through a circuit arises from the circuit itself. As the current increases, the magnetic flux through a loop due
More informationChapter 30 Inductance
Chapter 30 Inductance - Mutual Inductance - Self-Inductance and Inductors - Magnetic-Field Energy - The R- Circuit - The -C Circuit - The -R-C Series Circuit . Mutual Inductance - A changing current in
More informationSolution Derivations for Capa #11
Solution Derivations for Capa #11 Caution: The symbol E is used interchangeably for energy and EMF. 1) DATA: V b = 5.0 V, = 155 Ω, L = 8.400 10 2 H. In the diagram above, what is the voltage across the
More informationChapter 11. Inductors ISU EE. C.Y. Lee
Chapter 11 Inductors Objectives Describe the basic structure and characteristics of an inductor Discuss various types of inductors Analyze series inductors Analyze parallel inductors Analyze inductive
More informationHomework #11 203-1-1721 Physics 2 for Students of Mechanical Engineering
Homework #11 203-1-1721 Physics 2 for Students of Mechanical Engineering 2. A circular coil has a 10.3 cm radius and consists of 34 closely wound turns of wire. An externally produced magnetic field of
More informationThe purposes of this experiment are to test Faraday's Law qualitatively and to test Lenz's Law.
260 17-1 I. THEORY EXPERIMENT 17 QUALITATIVE STUDY OF INDUCED EMF Along the extended central axis of a bar magnet, the magnetic field vector B r, on the side nearer the North pole, points away from this
More informationElectroMagnetic Induction. AP Physics B
ElectroMagnetic Induction AP Physics B What is E/M Induction? Electromagnetic Induction is the process of using magnetic fields to produce voltage, and in a complete circuit, a current. Michael Faraday
More informationSlide 1 / 26. Inductance. 2011 by Bryan Pflueger
Slide 1 / 26 Inductance 2011 by Bryan Pflueger Slide 2 / 26 Mutual Inductance If two coils of wire are placed near each other and have a current passing through them, they will each induce an emf on one
More informationPhysics 2102 Lecture 19. Physics 2102
Physics 2102 Jonathan Dowling Physics 2102 Lecture 19 Ch 30: Inductors and RL Circuits Nikolai Tesla What are we going to learn? A road map Electric charge Electric force on other electric charges Electric
More informationModule 22: Inductance and Magnetic Field Energy
Module 22: Inductance and Magnetic Field Energy 1 Module 22: Outline Self Inductance Energy in Inductors Circuits with Inductors: RL Circuit 2 Faraday s Law of Induction dφ = B dt Changing magnetic flux
More informationEðlisfræði 2, vor 2007
[ Assignment View ] [ Print ] Eðlisfræði 2, vor 2007 30. Inductance Assignment is due at 2:00am on Wednesday, March 14, 2007 Credit for problems submitted late will decrease to 0% after the deadline has
More information12. The current in an inductor is changing at the rate of 100 A/s, and the inductor emf is 40 V. What is its self-inductance?
12. The current in an inductor is changing at the rate of 100 A/s, and the inductor emf is 40 V. What is its self-inductance? From Equation 32-5, L = -E=(dI =dt) = 40 V=(100 A/s) = 0.4 H. 15. A cardboard
More informationInductance and Magnetic Energy
Chapter 11 Inductance and Magnetic Energy 11.1 Mutual Inductance... 11-3 Example 11.1 Mutual Inductance of Two Concentric Coplanar Loops... 11-5 11. Self-Inductance... 11-5 Example 11. Self-Inductance
More informationInductors & Inductance. Electronic Components
Electronic Components Induction In 1824, Oersted discovered that current passing though a coil created a magnetic field capable of shifting a compass needle. Seven years later, Faraday and Henry discovered
More informationMagnetic Field of a Circular Coil Lab 12
HB 11-26-07 Magnetic Field of a Circular Coil Lab 12 1 Magnetic Field of a Circular Coil Lab 12 Equipment- coil apparatus, BK Precision 2120B oscilloscope, Fluke multimeter, Wavetek FG3C function generator,
More informationPhys222 Winter 2012 Quiz 4 Chapters 29-31. Name
Name If you think that no correct answer is provided, give your answer, state your reasoning briefly; append additional sheet of paper if necessary. 1. A particle (q = 5.0 nc, m = 3.0 µg) moves in a region
More informationObjectives. Capacitors 262 CHAPTER 5 ENERGY
Objectives Describe a capacitor. Explain how a capacitor stores energy. Define capacitance. Calculate the electrical energy stored in a capacitor. Describe an inductor. Explain how an inductor stores energy.
More informationLecture 22. Inductance. Magnetic Field Energy. Outline:
Lecture 22. Inductance. Magnetic Field Energy. Outline: Self-induction and self-inductance. Inductance of a solenoid. The energy of a magnetic field. Alternative definition of inductance. Mutual Inductance.
More informationChapter 27 Magnetic Field and Magnetic Forces
Chapter 27 Magnetic Field and Magnetic Forces - Magnetism - Magnetic Field - Magnetic Field Lines and Magnetic Flux - Motion of Charged Particles in a Magnetic Field - Applications of Motion of Charged
More informationLast time : energy storage elements capacitor.
Last time : energy storage elements capacitor. Charge on plates Energy stored in the form of electric field Passive sign convention Vlt Voltage drop across real capacitor can not change abruptly because
More information1. The diagram below represents magnetic lines of force within a region of space.
1. The diagram below represents magnetic lines of force within a region of space. 4. In which diagram below is the magnetic flux density at point P greatest? (1) (3) (2) (4) The magnetic field is strongest
More informationCircuits with inductors and alternating currents. Chapter 20 #45, 46, 47, 49
Circuits with inductors and alternating currents Chapter 20 #45, 46, 47, 49 RL circuits Ch. 20 (last section) Symbol for inductor looks like a spring. An inductor is a circuit element that has a large
More informationProblem 1 (25 points)
MASSACHUSETTS INSTITUTE OF TECHNOLOGY Department of Physics 8.02 Spring 2012 Exam Three Solutions Problem 1 (25 points) Question 1 (5 points) Consider two circular rings of radius R, each perpendicular
More informationModule P4.4 Electromagnetic induction
F L E X I B L E L E A R N I N G A P P R O A C H T O P H Y S I C S Module P4.4 Electromagnetic induction 1 Opening items 1.1 Module introduction 1.2 Fast track questions 1.3 Ready to study? 2 Introducing
More informationForce on Moving Charges in a Magnetic Field
[ Assignment View ] [ Eðlisfræði 2, vor 2007 27. Magnetic Field and Magnetic Forces Assignment is due at 2:00am on Wednesday, February 28, 2007 Credit for problems submitted late will decrease to 0% after
More informationAP2 Magnetism. (c) Explain why the magnetic field does no work on the particle as it moves in its circular path.
A charged particle is projected from point P with velocity v at a right angle to a uniform magnetic field directed out of the plane of the page as shown. The particle moves along a circle of radius R.
More informationFaraday s Law of Induction
Chapter 10 Faraday s Law of Induction 10.1 Faraday s Law of Induction...10-10.1.1 Magnetic Flux...10-3 10.1. Lenz s Law...10-5 10. Motional EMF...10-7 10.3 Induced Electric Field...10-10 10.4 Generators...10-1
More informationEE301 Lesson 14 Reading: 10.1-10.4, 10.11-10.12, 11.1-11.4 and 11.11-11.13
CAPACITORS AND INDUCTORS Learning Objectives EE301 Lesson 14 a. Define capacitance and state its symbol and unit of measurement. b. Predict the capacitance of a parallel plate capacitor. c. Analyze how
More informationPhysics 112 Homework 5 (solutions) (2004 Fall) Solutions to Homework Questions 5
Solutions to Homework Questions 5 Chapt19, Problem-2: (a) Find the direction of the force on a proton (a positively charged particle) moving through the magnetic fields in Figure P19.2, as shown. (b) Repeat
More informationCoupled Inductors. Introducing Coupled Inductors
Coupled Inductors From power distribution across large distances to radio transmissions, coupled inductors are used extensively in electrical applications. Their properties allow for increasing or decreasing
More informationScott Hughes 7 April 2005. Massachusetts Institute of Technology Department of Physics 8.022 Spring 2005. Lecture 15: Mutual and Self Inductance.
Scott Hughes 7 April 2005 151 Using induction Massachusetts nstitute of Technology Department of Physics 8022 Spring 2005 Lecture 15: Mutual and Self nductance nduction is a fantastic way to create EMF;
More informationChapter 7. Magnetism and Electromagnetism ISU EE. C.Y. Lee
Chapter 7 Magnetism and Electromagnetism Objectives Explain the principles of the magnetic field Explain the principles of electromagnetism Describe the principle of operation for several types of electromagnetic
More informationChapter 10. Faraday s Law of Induction
10 10 10-0 Chapter 10 Faraday s Law of Induction 10.1 Faraday s Law of Induction... 10-3 10.1.1 Magnetic Flux... 10-5 10.2 Motional EMF... 10-5 10.3 Faraday s Law (see also Faraday s Law Simulation in
More informationChapter 30 - Magnetic Fields and Torque. A PowerPoint Presentation by Paul E. Tippens, Professor of Physics Southern Polytechnic State University
Chapter 30 - Magnetic Fields and Torque A PowerPoint Presentation by Paul E. Tippens, Professor of Physics Southern Polytechnic State University 2007 Objectives: After completing this module, you should
More informationApril 1. Physics 272. Spring 2014 http://www.phys.hawaii.edu/~philipvd/pvd_14_spring_272_uhm.html. Prof. Philip von Doetinchem philipvd@hawaii.
Physics 272 April 1 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 - 164 Summary Gauss's
More informationEdmund Li. Where is defined as the mutual inductance between and and has the SI units of Henries (H).
INDUCTANCE MUTUAL INDUCTANCE If we consider two neighbouring closed loops and with bounding surfaces respectively then a current through will create a magnetic field which will link with as the flux passes
More informationMagnetic Circuits. Outline. Ampere s Law Revisited Review of Last Time: Magnetic Materials Magnetic Circuits Examples
Magnetic Circuits Outline Ampere s Law Revisited Review of Last Time: Magnetic Materials Magnetic Circuits Examples 1 Electric Fields Magnetic Fields S ɛ o E da = ρdv B V = Q enclosed S da =0 GAUSS GAUSS
More informationProblem Solving 8: RC and LR Circuits
MASSACHUSETTS INSTITUTE OF TECHNOLOGY Department of Physics Problem Solving 8: RC and LR Circuits Section Table and Group (e.g. L04 3C ) Names Hand in one copy per group at the end of the Friday Problem
More informationReading assignment: All students should read the Appendix about using oscilloscopes.
10. A ircuits* Objective: To learn how to analyze current and voltage relationships in alternating current (a.c.) circuits. You will use the method of phasors, or the vector addition of rotating vectors
More informationLesson 3 DIRECT AND ALTERNATING CURRENTS. Task. The skills and knowledge taught in this lesson are common to all missile repairer tasks.
Lesson 3 DIRECT AND ALTERNATING CURRENTS Task. The skills and knowledge taught in this lesson are common to all missile repairer tasks. Objectives. When you have completed this lesson, you should be able
More information104 Practice Exam 2-3/21/02
104 Practice Exam 2-3/21/02 1. Two electrons are located in a region of space where the magnetic field is zero. Electron A is at rest; and electron B is moving westward with a constant velocity. A non-zero
More informationElectromagnetism Laws and Equations
Electromagnetism Laws and Equations Andrew McHutchon Michaelmas 203 Contents Electrostatics. Electric E- and D-fields............................................. Electrostatic Force............................................2
More informationRUPHYS2272015 ( RUPHY227F2015 ) My Courses Course Settings University Physics with Modern Physics, 14e Young/Freedman
Signed in as Jolie Cizewski, Instructor Help Sign Out RUPHYS2272015 ( RUPHY227F2015 ) My Courses Course Settings University Physics with Modern Physics, 14e Young/Freedman Course Home Assignments Roster
More informationDC generator theory. Resources and methods for learning about these subjects (list a few here, in preparation for your research):
DC generator theory This worksheet and all related files are licensed under the Creative Commons Attribution License, version 1.0. To view a copy of this license, visit http://creativecommons.org/licenses/by/1.0/,
More informationDigital Energy ITI. Instrument Transformer Basic Technical Information and Application
g Digital Energy ITI Instrument Transformer Basic Technical Information and Application Table of Contents DEFINITIONS AND FUNCTIONS CONSTRUCTION FEATURES MAGNETIC CIRCUITS RATING AND RATIO CURRENT TRANSFORMER
More informationChapter 22: Electric motors and electromagnetic induction
Chapter 22: Electric motors and electromagnetic induction The motor effect movement from electricity When a current is passed through a wire placed in a magnetic field a force is produced which acts on
More informationConceptual: 1, 3, 5, 6, 8, 16, 18, 19. Problems: 4, 6, 8, 11, 16, 20, 23, 27, 34, 41, 45, 56, 60, 65. Conceptual Questions
Conceptual: 1, 3, 5, 6, 8, 16, 18, 19 Problems: 4, 6, 8, 11, 16, 20, 23, 27, 34, 41, 45, 56, 60, 65 Conceptual Questions 1. The magnetic field cannot be described as the magnetic force per unit charge
More informationPhysics 121 Sample Common Exam 3 NOTE: ANSWERS ARE ON PAGE 6. Instructions: 1. In the formula F = qvxb:
Physics 121 Sample Common Exam 3 NOTE: ANSWERS ARE ON PAGE 6 Signature Name (Print): 4 Digit ID: Section: Instructions: Answer all questions 24 multiple choice questions. You may need to do some calculation.
More informationCandidate Number. General Certificate of Education Advanced Level Examination June 2010
entre Number andidate Number Surname Other Names andidate Signature General ertificate of Education dvanced Level Examination June 1 Physics PHY4/1 Unit 4 Fields and Further Mechanics Section Friday 18
More informationMagnetism. d. gives the direction of the force on a charge moving in a magnetic field. b. results in negative charges moving. clockwise.
Magnetism 1. An electron which moves with a speed of 3.0 10 4 m/s parallel to a uniform magnetic field of 0.40 T experiences a force of what magnitude? (e = 1.6 10 19 C) a. 4.8 10 14 N c. 2.2 10 24 N b.
More informationEEE1001/PHY1002. Magnetic Circuits. The circuit is of length l=2πr. B andφ circulate
1 Magnetic Circuits Just as we view electric circuits as related to the flow of charge, we can also view magnetic flux flowing around a magnetic circuit. The sum of fluxes entering a point must sum to
More informationPHYS 222 Spring 2012 Final Exam. Closed books, notes, etc. No electronic device except a calculator.
PHYS 222 Spring 2012 Final Exam Closed books, notes, etc. No electronic device except a calculator. NAME: (all questions with equal weight) 1. If the distance between two point charges is tripled, the
More informationMagnetic Fields. I. Magnetic Field and Magnetic Field Lines
Magnetic Fields I. Magnetic Field and Magnetic Field Lines A. The concept of the magnetic field can be developed in a manner similar to the way we developed the electric field. The magnitude of the magnetic
More informationEE 221 Circuits II. Chapter 13 Magnetically Coupled Circuits
EE Circuits II Chapter 3 Magnetically Coupled Circuits Magnetically Coupled Circuits 3. What is a transformer? 3. Mutual Inductance 3.3 Energy in a Coupled Circuit 3.4 inear Transformers 3.5 Ideal Transformers
More informationElectromagnetic Induction: Faraday's Law
1 Electromagnetic Induction: Faraday's Law OBJECTIVE: To understand how changing magnetic fields can produce electric currents. To examine Lenz's Law and the derivative form of Faraday's Law. EQUIPMENT:
More informationMagnetic Fields and Their Effects
Name Date Time to Complete h m Partner Course/ Section / Grade Magnetic Fields and Their Effects This experiment is intended to give you some hands-on experience with the effects of, and in some cases
More informationMagnetic electro-mechanical machines
Magnetic electro-mechanical machines Lorentz Force A magnetic field exerts force on a moving charge. The Lorentz equation: f = q(e + v B) f: force exerted on charge q E: electric field strength v: velocity
More informationES250: Electrical Science. HW7: Energy Storage Elements
ES250: Electrical Science HW7: Energy Storage Elements Introduction This chapter introduces two more circuit elements, the capacitor and the inductor whose elements laws involve integration or differentiation;
More informationDIRECT CURRENT GENERATORS
DIRECT CURRENT GENERATORS Revision 12:50 14 Nov 05 INTRODUCTION A generator is a machine that converts mechanical energy into electrical energy by using the principle of magnetic induction. This principle
More informationELECTRODYNAMICS 05 AUGUST 2014
ELECTRODYNAMICS 05 AUGUST 2014 In this lesson we: Lesson Description Discuss the motor effect Discuss how generators and motors work. Summary The Motor Effect In order to realise the motor effect, the
More informationLast Name: First Name: Physics 102 Spring 2006: Exam #2 Multiple-Choice Questions 1. A charged particle, q, is moving with speed v perpendicular to a uniform magnetic field. A second identical charged
More informationCapacitors in Circuits
apacitors in ircuits apacitors store energy in the electric field E field created by the stored charge In circuit apacitor may be absorbing energy Thus causes circuit current to be reduced Effectively
More informationIntroduction to Electricity & Magnetism. Dr Lisa Jardine-Wright Cavendish Laboratory
Introduction to Electricity & Magnetism Dr Lisa Jardine-Wright Cavendish Laboratory Examples of uses of electricity Christmas lights Cars Electronic devices Human body Electricity? Electricity is the presence
More informationTEACHER S CLUB EXAMS GRADE 11. PHYSICAL SCIENCES: PHYSICS Paper 1
TEACHER S CLUB EXAMS GRADE 11 PHYSICAL SCIENCES: PHYSICS Paper 1 MARKS: 150 TIME: 3 hours INSTRUCTIONS AND INFORMATION 1. This question paper consists of 12 pages, two data sheets and a sheet of graph
More informationMotor Fundamentals. DC Motor
Motor Fundamentals Before we can examine the function of a drive, we must understand the basic operation of the motor. It is used to convert the electrical energy, supplied by the controller, to mechanical
More informationPhysics 25 Exam 3 November 3, 2009
1. A long, straight wire carries a current I. If the magnetic field at a distance d from the wire has magnitude B, what would be the the magnitude of the magnetic field at a distance d/3 from the wire,
More informationReview Questions PHYS 2426 Exam 2
Review Questions PHYS 2426 Exam 2 1. If 4.7 x 10 16 electrons pass a particular point in a wire every second, what is the current in the wire? A) 4.7 ma B) 7.5 A C) 2.9 A D) 7.5 ma E) 0.29 A Ans: D 2.
More informationW03 Analysis of DC Circuits. Yrd. Doç. Dr. Aytaç Gören
W03 Analysis of DC Circuits Yrd. Doç. Dr. Aytaç Gören ELK 2018 - Contents W01 Basic Concepts in Electronics W02 AC to DC Conversion W03 Analysis of DC Circuits (self and condenser) W04 Transistors and
More informationCandidate Number. General Certificate of Education Advanced Level Examination June 2014
entre Number andidate Number Surname Other Names andidate Signature General ertificate of Education dvanced Level Examination June 214 Physics PHY4/1 Unit 4 Fields and Further Mechanics Section Wednesday
More informationAC generator theory. Resources and methods for learning about these subjects (list a few here, in preparation for your research):
AC generator theory This worksheet and all related files are licensed under the Creative Commons Attribution License, version 1.0. To view a copy of this license, visit http://creativecommons.org/licenses/by/1.0/,
More informationSTUDY MATERIAL FOR CLASS 10+2 - Physics- CURRENT ELECTRICITY. The flow of electric charges in a particular direction constitutes electric current.
Chapter : 3 Current Electricity Current Electricity The branch of Physics which deals with the study of electric charges in motion is called current electricity. Electric current The flow of electric charges
More information45. The peak value of an alternating current in a 1500-W device is 5.4 A. What is the rms voltage across?
PHYS Practice Problems hapters 8- hapter 8. 45. The peak value of an alternating current in a 5-W device is 5.4 A. What is the rms voltage across? The power and current can be used to find the peak voltage,
More informationEðlisfræði 2, vor 2007
[ Assignment View ] [ Pri Eðlisfræði 2, vor 2007 28. Sources of Magnetic Field Assignment is due at 2:00am on Wednesday, March 7, 2007 Credit for problems submitted late will decrease to 0% after the deadline
More informationInductors in AC Circuits
Inductors in AC Circuits Name Section Resistors, inductors, and capacitors all have the effect of modifying the size of the current in an AC circuit and the time at which the current reaches its maximum
More informationMagnetic Dipoles. Recall that an electric dipole consists of two equal but opposite charges separated by some distance, such as in
MAGNETISM History of Magnetism Bar Magnets Magnetic Dipoles Magnetic Fields Magnetic Forces on Moving Charges and Wires Electric Motors Current Loops and Electromagnets Solenoids Sources of Magnetism Spin
More informationLinear DC Motors. 15.1 Magnetic Flux. 15.1.1 Permanent Bar Magnets
Linear DC Motors The purpose of this supplement is to present the basic material needed to understand the operation of simple DC motors. This is intended to be used as the reference material for the linear
More informationCurrent, Resistance and Electromotive Force. Young and Freedman Chapter 25
Current, Resistance and Electromotive Force Young and Freedman Chapter 25 Electric Current: Analogy, water flowing in a pipe H 2 0 gallons/minute Flow Rate is the NET amount of water passing through a
More informationOutline. Systems and Signals 214 / 244 & Energy Systems 244 / 344. Ideal Inductor. Ideal Inductor (cont... )
Outline Systems and Signals 214 / 244 & Energy Systems 244 / 344 Inductance, Leakage Inductance, Mutual Inductance & Transformers 1 Inductor revision Ideal Inductor Non-Ideal Inductor Dr. P.J. Randewijk
More informationMULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) If the voltage at a point in space is zero, then the electric field must be A) zero. B) positive.
More informationEDEXCEL NATIONAL CERTIFICATE/DIPLOMA UNIT 5 - ELECTRICAL AND ELECTRONIC PRINCIPLES NQF LEVEL 3 OUTCOME 4 - ALTERNATING CURRENT
EDEXCEL NATIONAL CERTIFICATE/DIPLOMA UNIT 5 - ELECTRICAL AND ELECTRONIC PRINCIPLES NQF LEVEL 3 OUTCOME 4 - ALTERNATING CURRENT 4 Understand single-phase alternating current (ac) theory Single phase AC
More informationChapter 7 Direct-Current Circuits
Chapter 7 Direct-Current Circuits 7. Introduction...7-7. Electromotive Force...7-3 7.3 Resistors in Series and in Parallel...7-5 7.4 Kirchhoff s Circuit Rules...7-7 7.5 Voltage-Current Measurements...7-9
More informationGeneral Physics (PHY 2140)
General Physics (PHY 2140) Lecture 12 Electricity and Magnetism Magnetism Magnetic fields and force Application of magnetic forces http://www.physics.wayne.edu/~apetrov/phy2140/ Chapter 19 1 Department
More informationPhysics 30 Worksheet #10 : Magnetism From Electricity
Physics 30 Worksheet #10 : Magnetism From Electricity 1. Draw the magnetic field surrounding the wire showing electron current below. x 2. Draw the magnetic field surrounding the wire showing electron
More informationDOE FUNDAMENTALS HANDBOOK ELECTRICAL SCIENCE Volume 3 of 4
DOE-HDBK-1011/3-92 JUNE 1992 DOE FUNDAMENTALS HANDBOOK ELECTRICAL SCIENCE Volume 3 of 4 U.S. Department of Energy Washington, D.C. 20585 FSC-6910 Distribution Statement A. Approved for public release;
More informationBASIC ELECTRONICS AC CIRCUIT ANALYSIS. December 2011
AM 5-202 BASIC ELECTRONICS AC CIRCUIT ANALYSIS December 2011 DISTRIBUTION RESTRICTION: Approved for Pubic Release. Distribution is unlimited. DEPARTMENT OF THE ARMY MILITARY AUXILIARY RADIO SYSTEM FORT
More informationAn equivalent circuit of a loop antenna.
3.2.1. Circuit Modeling: Loop Impedance A loop antenna can be represented by a lumped circuit when its dimension is small with respect to a wavelength. In this representation, the circuit parameters (generally
More information1. Units of a magnetic field might be: A. C m/s B. C s/m C. C/kg D. kg/c s E. N/C m ans: D
Chapter 28: MAGNETIC FIELDS 1 Units of a magnetic field might be: A C m/s B C s/m C C/kg D kg/c s E N/C m 2 In the formula F = q v B: A F must be perpendicular to v but not necessarily to B B F must be
More informationThink About This How do the generators located inside the dam convert the kinetic and potential energy of the water into electric energy?
What You ll Learn You will describe how changing magnetic fields can generate electric potential differences. You will apply this phenomenon to the construction of generators and transformers. Why It s
More information13 ELECTRIC MOTORS. 13.1 Basic Relations
13 ELECTRIC MOTORS Modern underwater vehicles and surface vessels are making increased use of electrical actuators, for all range of tasks including weaponry, control surfaces, and main propulsion. This
More informationSimple Analysis for Brushless DC Motors Case Study: Razor Scooter Wheel Motor
Simple Analysis for Brushless DC Motors Case Study: Razor Scooter Wheel Motor At first glance, a brushless direct-current (BLDC) motor might seem more complicated than a permanent magnet brushed DC motor,
More informationCHAPTER - 1. Chapter ONE: WAVES CHAPTER - 2. Chapter TWO: RAY OPTICS AND OPTICAL INSTRUMENTS. CHAPTER - 3 Chapter THREE: WAVE OPTICS PERIODS PERIODS
BOARD OF INTERMEDIATE EDUCATION, A.P., HYDERABAD REVISION OF SYLLABUS Subject PHYSICS-II (w.e.f 2013-14) Chapter ONE: WAVES CHAPTER - 1 1.1 INTRODUCTION 1.2 Transverse and longitudinal waves 1.3 Displacement
More informationPrinciples and Working of DC and AC machines
BITS Pilani Dubai Campus Principles and Working of DC and AC machines Dr Jagadish Nayak Constructional features BITS Pilani Dubai Campus DC Generator A generator consists of a stationary portion called
More informationDC GENERATOR THEORY. LIST the three conditions necessary to induce a voltage into a conductor.
DC Generators DC generators are widely used to produce a DC voltage. The amount of voltage produced depends on a variety of factors. EO 1.5 LIST the three conditions necessary to induce a voltage into
More informationExercises on Voltage, Capacitance and Circuits. A d = (8.85 10 12 ) π(0.05)2 = 6.95 10 11 F
Exercises on Voltage, Capacitance and Circuits Exercise 1.1 Instead of buying a capacitor, you decide to make one. Your capacitor consists of two circular metal plates, each with a radius of 5 cm. The
More informationAircraft Electrical System
Chapter 9 Aircraft Electrical System Introduction The satisfactory performance of any modern aircraft depends to a very great degree on the continuing reliability of electrical systems and subsystems.
More informationE/M Experiment: Electrons in a Magnetic Field.
E/M Experiment: Electrons in a Magnetic Field. PRE-LAB You will be doing this experiment before we cover the relevant material in class. But there are only two fundamental concepts that you need to understand.
More informationMEASURING INSTRUMENTS. By: Nafees Ahmed, Asstt, Prof, EE Deptt, DIT, Dehradun
MEASURING INSTRUMENTS By: Nafees Ahmed, Asstt, Prof, EE Deptt, DIT, Dehradun MEASURING INSTRUMENTS The device used for comparing the unknown quantity with the unit of measurement or standard quantity is
More informationDEGREE: Bachelor's Degree in Industrial Electronics and Automation COURSE: 1º TERM: 2º WEEKLY PLANNING
SESSION WEEK COURSE: Physics II DEGREE: Bachelor's Degree in Industrial Electronics and Automation COURSE: 1º TERM: 2º WEEKLY PLANNING DESCRIPTION GROUPS (mark ) Indicate YES/NO If the session needs 2
More information