Faraday's Law ds B B G G ΦB B ds Φ ε = d B dt
|
|
- Gordon Kelly
- 6 years ago
- Views:
Transcription
1 Faraday's Law ds ds ε= d Φ dt Φ
2 Global Review Electrostatics» motion of q in external E-field» E-field generated by Σq i Magnetostatics» motion of q and i in external -field» -field generated by I Electrodynamics» time dependent -field generates E-field ac circuits, inductors, transformers, etc» time dependent E-field generates -field electromagnetic radiation - light
3 Overview of Lecture Induction Effects Faraday s Law (Lenz Law) Energy Conservation with induced currents? Faraday s Law in terms of Electric Fields Text Reference: Chapter 33: 1-5
4 Induction Effects ar magnet moves through coil Current induced in coil S N v Change pole that enters Induced current changes sign N S v ar magnet stationary inside coil No current induced in coil N S Coil moves past fixed bar magnet Current induced in coil S N v
5 Induction Effects from Currents Switch closed (or opened) current induced in coil b Steady state current in coil a no current induced in coil b b a Conclusion: A current is induced in a loop when: there is a change in magnetic field through it this can happen many different ways How can we quantify this?
6 An example of induction A wire loop falling into an increasing magnetic field time Force acting on moving charges magnetic field downward velocity N N N
7 Faraday's Law Define the flux of the magnetic field through an open surface as: ds Φ ds Faraday's Law: The emf induced in a circuit is determined by the time rate of change of the magnetic flux through that circuit. ε= d Φ dt So what is this emf?? The minus sign indicates direction of induced current (given by Lenz's Law).
8 electro-motive force or emf time A magnetic field, increasing in time, passes through the blue loop An electric field is generated ringing the increasing magnetic field Ringing electric field will drive currents, just like a voltage difference Loop integral of E-field is the emf ε = E dl
9 Lenz's Law: Lenz's Law The induced current will appear in such a direction that it opposes the change in flux that produced it. S N v N S v Conservation of energy considerations: 1 Claim: Direction of induced current must be so as to oppose the change; otherwise conservation of energy would be violated.» Why??? If current reinforced the change, then the change would get bigger and that would in turn induce a larger current which would increase the change, etc..
10 ACT 1 A conducting rectangular loop moves with constant velocity v in the +x direction through a region of constant magnetic field in the -z direction as shown. 1A What is the direction of the induced current in the loop? y X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X vx X X X X X X X X X X X X X X X X x (a) ccw (b) cw (c) no induced current A conducting rectangular loop moves with y constant velocity v in the -y direction and a constant current I flows in the +x direction as shown. What is the direction of the induced 1 current in the loop? (a) ccw (b) cw (c) no induced current v I x
11 ACT 1 A conducting rectangular loop moves with constant velocity v in the +x direction through a region of constant magnetic field in the -z direction as shown. 1A What is the direction of the induced current in the loop? (a) ccw (b) cw y X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X vx X X X X X X X X X X X X X X X X x (c) no induced current There is a non-zero flux Φ passing through the loop since is perpendicular to the area of the loop. Since the velocity of the loop and the magnetic field are CONSTANT, however, this flux DOES NOT CHANGE IN TIME. Therefore, there is NO emf induced in the loop; NO current will flow!!
12 ACT 1 A conducting rectangular loop moves with constant velocity v in the +x direction through a region of constant magnetic field in the -z direction as shown. 1A What is the direction of the induced current in the loop? y X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X vx X X X X X X X X X X X X X X X X x (a) ccw (b) cw (c) no induced current A conducting rectangular loop moves with y constant velocity v in the -y direction and a constant current I flows in the +x direction as shown. What is the direction of the induced 1 current in the loop? (a) ccw (b) cw (c) no induced current The flux through this loop DOES change in time since the loop is moving from a region of higher magnetic field to a region of lower field. Therefore, by Lenz Law, an emf will be induced which will oppose the change of flux. The current i is induced in the clockwise direction to restore the flux. i v I x
13 Calculation Suppose we pull with velocity v a coil of resistance R through a region of constant magnetic field. What will be the induced current?» What direction? Lenz Law clockwise!! What is the magnitude?» Magnetic Flux: Φ = xw x x x x x x x x x x x x x x x x x x x x x x x x x I w v» Faraday s Law: ε= d Φ dt d Φ w dx = = wv dt dt I ε = = R wv R
14 Energy Conservation? The induced current gives rise to a net magnetic force ( F ) on the loop which opposes the motion. F 2 2 wv = Iw= R w w v = R Energy is dissipated in circuit at rate P' F F' x x x x x x x x x x x x x x x x x x x x x x x x F' x P = Fv = I I = w w v R wv R Agent must exert equal but opposite force to move the loop with velocity v; agent does work at rate P, where v 2 = = wv P I R R = R w v R P = P'!
15 / t E Faraday's law a changing induces an emf which can produce a current in a loop. In order for charges to move (i.e., the current) there must be an electric field. we can state Faraday's law more generally in terms of the E field which is produced by a changing field. x x x E x x x x x x x E x x x x x x x x x x r x x x x x x x x x x x x x x x x x x x x E x x x x x x x x E x x Suppose is increasing into the screen as shown above. An E field is induced in the direction shown. To move a charge q around the circle would require an amount of work = W = qe dl This work can also be calculated from ε = W/q.
16 / t E Putting these 2 eqns together: W = qe dl ε = E dl ε= W q Therefore, Faraday's law can be rewritten in terms of the fields as: x x x E x x x x x x x E x x x x x x x x x x r x x x x x x x x x x x x x x x x x x x x E x x x x x x x x E x x Line integral d E dl = Φ Rate of change of around loop dt flux through loop 3 Note that E dl = 0 for E fields generated by charges at rest (electrostatics) since this would correspond to the potential difference between a point and itself. Consequently, there can be no "potential function" corresponding to these induced E fields.
17 3A ACT 2 The magnetic field in a region of space of radius 2R is aligned with the z-direction and changes in time as shown in the plot. What is sign of the induced emf in a ring of radius R at time t=t 1? (a) ε < 0 ( E ccw) (b) ε = 0 (c) ε > 0 ( E cw) X X X X X X X X X X X X X X X X X X X X X X X X X X X X R X X X X X X X X X X X X X X X X X X X X X X X X X X X X z y x 3 What is the relation between the magnitudes of the induced electric fields E R at radius R and E 2R at radius 2R? t 1 t (a) E 2R = E R (b) E 2R = 2E R (c) E 2R = 4E R
18 3A ACT 2 The magnetic field in a region of space of radius 2R is aligned with the z-direction and changes in time as shown in the plot. What is sign of the induced emf in a ring of radius R at time t=t 1? (a) ε < 0 ( E ccw) (b) ε = 0 (c) ε > 0 ( E cw) X X X X X X X X X X X X X X X X X X X X X X X X X X X X R X X X X X X X X X X X X X X X X X X X X X X X X X X X X z y x There will be an induced emf at t=t 1 because the magnetic field (and therefore the magnetic flux) is changing. It makes NO DIFFERENCE that at t=t 1 the magnetic field happens to be equal to ZERO! The magnetic field is increasing at t=t 1 (actually at all times shown!) which induces an emf which opposes the corresponding change in flux. ie electric field must be induced in a clockwise sense so that the current it would drive would create a magnetic field in the -z direction. t 1 Note: the signs work this way: E cw > 0 means that ds points in -z direction. d/dt > 0 dφ/dt < 0 Faraday s Law ε = - dφ/dt > 0 t
19 3A ACT 2 The magnetic field in a region of space of radius 2R is aligned with the z-direction and changes in time as shown in the plot. What is sign of the induced emf in a ring of radius R at time t=t 1? (a) ε < 0 ( E ccw) (b) ε = 0 (c) ε > 0 ( E cw) X X X X X X X X X X X X X X X X X X X X X X X X X X X X R X X X X X X X X X X X X X X X X X X X X X X X X X X X X z y x 3 What is the relation between the magnitudes of the induced electric fields E R at radius R and E 2R at radius 2R? t 1 t (a) E 2R = E R (b) E 2R = 2E R (c) E 2R = 4E R The rate of change of the flux is proportional to the area: The path integral of the induced electric field is proportional to the radius. dφ d = πr 2 dt dt E dl = E( 2πR) E R
20 Demo E-M Cannon Connect solenoid to a source of alternating voltage. The flux through the area to axis of solenoid therefore changes in time. A conducting ring placed on top of the solenoid will have a current induced in it opposing this change. v side view F ~ There will then be a force on the ring since it contains a current which is circulating in the presence of a magnetic field. 2 F top view
21 2A ACT 3 For this ACT, we will predict the results of variants of the electromagnetic cannon demo. Suppose two aluminum rings are used in the demo; Ring 2 is identical to Ring 1 except that it has a small slit as shown. Let F 1 be the force on Ring 1; F 2 be the force on Ring 2. Ring 1 Ring 2 (a) F 2 < F 1 (b) F 2 = F 1 (c) F 2 > F 1 2 Suppose two identically shaped rings are used in the demo. Ring 1 is made of copper (resistivity = 1.7X10-8 Ω-m); Ring 2 is made of aluminum (resistivity = 2.8X10-8 Ω-m). Let F 1 be the force on Ring 1; F 2 be the force on Ring 2. (a) F 2 < F 1 (b) F 2 = F 1 (c) F 2 > F 1
22 2A ACT 3 For this ACT, we will predict the results of variants of the electromagnetic cannon demo which you just observed. Suppose two aluminum rings are used in the demo; Ring 2 is identical to Ring 1 except that it has a small slit as shown. Let F 1 be the force on Ring 1; F 2 be the force on Ring 2. (a) F 2 < F 1 (b) F 2 = F 1 (c) F 2 > F 1 Ring 1 Ring 2 The key here is to realize exactly how the force on the ring is produced. A force is exerted on the ring because a current is flowing in the ring and the ring is located in a magnetic field with a component perpendicular to the current. An emf is induced in Ring 2 equal to that of Ring 1, but NO CURRENT is induced in Ring 2 because of the slit! Therefore, there is NO force on Ring 2!
23 2A ACT 3 For this ACT, we will predict the results of variants of the electromagnetic cannon demo which you just observed. Suppose two aluminum rings are used in the demo; Ring 2 is identical to Ring 1 except that it has a small slit as shown. Let F 1 be the force on Ring 1; F 2 be the force on Ring 2. (a) F 2 < F 1 (b) F 2 = F 1 (c) F 2 > F 1 Ring 1 Ring 2 2 Suppose two identically shaped rings are used in the demo. Ring 1 is made of copper (resistivity = 1.7X10-8 Ω-m); Ring 2 is made of aluminum (resistivity = 2.8X10-8 Ω-m). Let F 1 be the force on Ring 1; F 2 be the force on Ring 2. (a) F 2 < F 1 (b) F 2 = F 1 (c) F 2 > F 1 The emf s induced in each ring are equal. The currents induced in each ring are NOT equal because of the different resistivities. The copper ring will have a larger current induced (smaller resistance) and therefore will experience a larger force (F proportional to current).
General Review. LECTURE 16 Faraday s Law of Induction
Electrostatics General Review Motion of q in eternal E-field E-field generated b Sq i Magnetostatics Motion of q and I in eternal B-field B-field generated b I Electrodnamics Time dependent B-field generates
More informationPhysics 1402: Lecture 18 Today s Agenda
Physics 1402: Lecture 18 Today s Agenda Announcements: Midterm 1 distributed available Homework 05 due Friday Magnetism Calculation of Magnetic Field Two ways to calculate the Magnetic Field: iot-savart
More informationPhysics 1402: Lecture 19 Today s Agenda
Physics 1402: Lecture 19 Today s Agenda Announcements: Midterm 1 aailable Homework 06 next Friday Induction Faraday's Law d 1 Induction Effects ar magnet moes through coil Current induced in coil Change
More informationRecap (1) Maxwell s Equations describe the electric field E and magnetic field B generated by stationary charge density ρ and current density J:
Class 13 : Induction Phenomenon of induction and Faraday s Law How does a generator and transformer work? Self- and mutual inductance Energy stored in B-field Recap (1) Maxwell s Equations describe the
More informationElectricity & Optics
Physics 24100 Electricity & Optics Lecture 16 Chapter 28 sec. 1-3 Fall 2017 Semester Professor Koltick Magnetic Flux We define magnetic flux in the same way we defined electric flux: φ e = n E da φ m =
More informationFARADAY S AND LENZ LAW B O O K P G
FARADAY S AND LENZ LAW B O O K P G. 4 3 6-438 MOTIONAL EMF AND MAGNETIC FLUX (DERIVIATION) Motional emf = vbl Let a conducting rod being moved through a magnetic field B During time t 0 the rod has been
More informationMotional EMF. Toward Faraday's Law. Phys 122 Lecture 21
Motional EMF Toward Faraday's Law Phys 122 Lecture 21 Move a conductor in a magnetic field Conducting rail 1. ar moves 2. EMF produced 3. Current flows 4. ulb glows The ig Idea is the induced emf When
More informationChapter 21 Magnetic Induction Lecture 12
Chapter 21 Magnetic Induction Lecture 12 21.1 Why is it called Electromagnetism? 21.2 Magnetic Flux and Faraday s Law 21.3 Lenz s Law and Work-Energy Principles 21.4 Inductance 21.5 RL Circuits 21.6 Energy
More informationFaraday s Law. Underpinning of Much Technology
Module 21: Faraday s Law 1 Faraday s Law Fourth (Final) Maxwell s Equation Underpinning of Much Technology 2 Demonstration: Falling Magnet 3 Magnet Falling Through a Ring Link to movie Falling magnet slows
More informationPhysics 54 Lecture March 1, Micro-quiz problems (magnetic fields and forces) Magnetic dipoles and their interaction with magnetic fields
Physics 54 Lecture March 1, 2012 OUTLINE Micro-quiz problems (magnetic fields and forces) Magnetic dipoles and their interaction with magnetic fields Electromagnetic induction Introduction to electromagnetic
More informationElectromagnetic Induction Practice Problems Homework PSI AP Physics B
Electromagnetic Induction Practice Problems Homework PSI AP Physics B Name Multiple Choice Questions 1. A square loop of wire is placed in a uniform magnetic field perpendicular to the magnetic lines.
More informationCHAPTER 29: ELECTROMAGNETIC INDUCTION
CHAPTER 29: ELECTROMAGNETIC INDUCTION So far we have seen that electric charges are the source for both electric and magnetic fields. We have also seen that these fields can exert forces on other electric
More informationLast Homework. Reading: Chap. 33 and Chap. 33. Suggested exercises: 33.1, 33.3, 33.5, 33.7, 33.9, 33.11, 33.13, 33.15,
Chapter 33. Electromagnetic Induction Electromagnetic induction is the scientific principle that underlies many modern technologies, from the generation of electricity to communications and data storage.
More informationSliding Conducting Bar
Motional emf, final For equilibrium, qe = qvb or E = vb A potential difference is maintained between the ends of the conductor as long as the conductor continues to move through the uniform magnetic field
More informationPHYSICS Fall Lecture 15. Electromagnetic Induction and Faraday s Law
PHYSICS 1444-001 Fall 2012 Lecture 15 Electromagnetic Induction and Faraday s Law A current can be produced by a changing magnetic field First shown in an experiment by Michael Faraday Induced emf A primary
More informationChapter 27, 28 & 29: Magnetism & Electromagnetic Induction. Magnetic flux Faraday s and Lenz s law Electromagnetic Induction Ampere s law
Chapter 27, 28 & 29: Magnetism & Electromagnetic Induction Magnetic flux Faraday s and Lenz s law Electromagnetic Induction Ampere s law 1 Magnetic Flux and Faraday s Law of Electromagnetic Induction We
More informationCourse Updates. 2) Assignment #9 posted by Friday (due Mar 29)
Course Updates http://www.phys.hawaii.edu/~varner/phys272-spr10/physics272.html Reminders: 1) Assignment #8 due now 2) Assignment #9 posted by Friday (due Mar 29) 3) Chapter 29 this week (start Inductance)
More informationLECTURE 23 INDUCED EMF. Instructor: Kazumi Tolich
LECTURE 23 INDUCED EMF Instructor: Kazumi Tolich Lecture 23 2 Reading chapter 23.1 to 23.4. Induced emf Magnetic flux Faraday s law Lenz s law Quiz: 1 3 Consider the circuits shown. Which of the following
More informationLecture 29: MON 03 NOV
Physics 2113 Jonathan Dowling Lecture 29: MON 03 NOV Ch30.1 4 Induction and Inductance I Fender Stratocaster Solenoid Pickup Magnetic Circuit Breaker As the normal operating or "rated" current flows through
More informationiclicker: which statements are correct?
iclicker: which statements are correct? 1. Electric field lines must originate and terminate on charges 2. Magnetic field lines are always closed A: 1&2 B: only 1 C: only 2 D: neither 2 Inductive E-field:
More informationInduction and Inductance
Welcome Back to Physics 1308 Induction and Inductance Michael Faraday 22 September 1791 25 August 1867 Announcements Assignments for Tuesday, November 6th: - Reading: Chapter 30.6-30.8 - Watch Videos:
More informationChapter 20: Electromagnetic Induction. PHY2054: Chapter 20 1
Chapter 20: Electromagnetic Induction PHY2054: Chapter 20 1 Electromagnetic Induction Magnetic flux Induced emf Faraday s Law Lenz s Law Motional emf Magnetic energy Inductance RL circuits Generators and
More informationGeneral Physics II. Electromagnetic Induction and Electromagnetic Waves
General Physics II Electromagnetic Induction and Electromagnetic Waves 1 Induced emf We have seen that an electric current produces a magnetic field. Michael Faraday demonstrated that a magnetic field
More information21 MAGNETIC FORCES AND MAGNETIC FIELDS
CHAPTER 1 MAGNETIC FORCES AND MAGNETIC FIELDS ANSWERS TO FOCUS ON CONCEPTS QUESTIONS 1 (d) Right-Hand Rule No 1 gives the direction of the magnetic force as x for both drawings A and B In drawing C, the
More informationLECTURE 17. Reminder Magnetic Flux
LECTURE 17 Motional EMF Eddy Currents Self Inductance Reminder Magnetic Flux Faraday s Law ε = dφ B Flux through one loop Φ B = BAcosθ da Flux through N loops Φ B = NBAcosθ 1 Reminder How to Change Magnetic
More informationPHYSICS 1B. Today s lecture: Motional emf. and. Lenz s Law. Electricity & Magnetism
PHYSICS 1B Today s lecture: Motional emf and Lenz s Law Electricity & Magnetism PHYSICS 1B Faraday s Law Applications of Faraday s Law - GFCI A GFCI is a Ground Fault Circuit Interrupter. It is designed
More informationAP Physics C Unit 11: Electromagnetic Induction. Part 1 - Faraday s Law and Lenz s Law
AP Physics C Unit 11: Electromagnetic Induction Part 1 - Faraday s Law and Lenz s Law What is E/M Induction? Electromagnetic Induction is the process of using magnetic fields to produce voltage, and in
More informationLast time. Ampere's Law Faraday s law
Last time Ampere's Law Faraday s law 1 Faraday s Law of Induction (More Quantitative) The magnitude of the induced EMF in conducting loop is equal to the rate at which the magnetic flux through the surface
More informationChapter 9 FARADAY'S LAW Recommended Problems:
Chapter 9 FARADAY'S LAW Recommended Problems: 5,7,9,10,11,13,15,17,20,21,28,29,31,32,33,34,49,50,52,58,63,64. Faraday's Law of Induction We learned that e. current produces magnetic field. Now we want
More informationLecture 10 Induction and Inductance Ch. 30
Lecture 10 Induction and Inductance Ch. 30 Cartoon - Faraday Induction Opening Demo - Thrust bar magnet through coil and measure the current Topics Faraday s Law Lenz s Law Motional Emf Eddy Currents LR
More informationPHY101: Major Concepts in Physics I
Welcome back to PHY101: Major Concepts in Physics I Photo: J. M. Schwarz Announcements In class today we will finish Chapter 20 (sections 3, 4, and 7). and then move to Chapter 13 (the first six sections).
More informationGeneral Physics (PHY 2140)
General Physics (PHY 2140) Lecture 15 Electricity and Magnetism Magnetism Applications of magnetic forces Induced voltages and induction Magnetic flux and induced emf Faraday s law http://www.physics.wayne.edu/~apetrov/phy2140/
More informationLecture 30: WED 04 NOV
Physics 2113 Jonathan Dowling Lecture 30: WED 04 NOV Induction and Inductance II Fender Stratocaster Solenoid Pickup F a r a d a y ' s E x p e r i m e n t s I n a s e r i e s o f e x p e r i m e n t s,
More informationLecture 29: MON 02 NOV
Physics 2113 Jonathan Dowling Lecture 29: MON 02 NOV Induction and Inductance I Fender Stratocaster Solenoid Pickup F a r a d a y ' s E x p e r i m e n t s I n a s e r i e s o f e x p e r i m e n t s,
More informationAgenda for Today. Elements of Physics II. Forces on currents
Forces on currents Physics 132: Lecture e 14 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 informationInduction and inductance
PH -C Fall 01 Induction and inductance Lecture 15 Chapter 30 (Halliday/Resnick/Walker, Fundamentals of Physics 8 th etion) 1 Chapter 30 Induction and Inductance In this chapter we will study the following
More informationFaraday s Law; Inductance
This test covers Faraday s Law of induction, motional emf, Lenz s law, induced emf and electric fields, eddy currents, self-inductance, inductance, RL circuits, and energy in a magnetic field, with some
More informationConcept Questions with Answers. Concept Questions with Answers W11D2. Concept Questions Review
Concept Questions with W11D2 Concept Questions Review W11D2 2 Concept Questions with W7D1 W07D1 Magnetic Dipoles, Force and Torque on a Dipole, Experiment 2 W07D1 Magnetic Dipoles, Torque and Force on
More informationVersion 001 HW 22 EM Induction C&J sizemore (21301jtsizemore) 1
Version 001 HW 22 EM Induction C&J sizemore (21301jtsizemore) 1 This print-out should have 35 questions. Multiple-choice questions may continue on the next column or page find all choices before answering.
More informationChapters 34,36: Electromagnetic Induction. PHY2061: Chapter
Chapters 34,36: Electromagnetic Induction PHY2061: Chapter 34-35 1 Electromagnetic Induction Magnetic flux Induced emf Faraday s Law Lenz s Law Motional emf Magnetic energy Inductance RL circuits Generators
More informationPhysics 182. Assignment 4
Physics 182 Assignment 4 1. A dipole (electric or magnetic) in a non-uniform field will in general experience a net force. The electric case was the subject of a problem on the midterm exam; here we examine
More informationRevision Guide for Chapter 15
Revision Guide for Chapter 15 Contents tudent s Checklist Revision otes Transformer... 4 Electromagnetic induction... 4 Generator... 5 Electric motor... 6 Magnetic field... 8 Magnetic flux... 9 Force on
More informationElectromagnetic Induction. Bo Zhou Faculty of Science, Hokudai
Electromagnetic Induction Bo Zhou Faculty of Science, Hokudai Oersted's law Oersted s discovery in 1820 that there was a close connection between electricity and magnetism was very exciting until then,
More informationLenz s Law (Section 22.5)
Lenz s Law (Section 22.5) : Thursday, 25 of February 7:00 9:00 pm Rooms: Last Name Room (Armes) Seats A - F 201 122 G - R 200 221 S - Z 205 128 2016-02-21 Phys 1030 General Physics II (Gericke) 1 1) Charging
More informationPHYSICS - GIANCOLI CALC 4E CH 29: ELECTROMAGNETIC INDUCTION.
!! www.clutchprep.com CONCEPT: ELECTROMAGNETIC INDUCTION A coil of wire with a VOLTAGE across each end will have a current in it - Wire doesn t HAVE to have voltage source, voltage can be INDUCED i V Common
More informationElectromagnetic Induction
Electromagnetic Induction Name Section Theory Electromagnetic induction employs the concept magnetic flux. Consider a conducting loop of area A in a magnetic field with magnitude B. The flux Φ is proportional
More informationPhysics 4. Magnetic Induction. Prepared by Vince Zaccone For Campus Learning Assistance Services at UCSB
Physics 4 Magnetic Induction Before we can talk about induction we need to understand magnetic flux. You can think of flux as the number of field lines passing through an area. Here is the formula: flux
More informationPhysics 201. Professor P. Q. Hung. 311B, Physics Building. Physics 201 p. 1/1
Physics 201 p. 1/1 Physics 201 Professor P. Q. Hung 311B, Physics Building Physics 201 p. 2/1 Magnetic flux What is a magnetic flux? This is very similar to the concept of an electric flux through an area
More informationPhysics 169. Luis anchordoqui. Kitt Peak National Observatory. Monday, March 27, 17
Physics 169 Kitt Peak National Observatory Luis anchordoqui 1 Question teady electric current can give steady magnetic field Because of symmetry between electricity and magnetism we can ask: teady magnetic
More informationDemo: Solenoid and Magnet. Topics. Chapter 22 Electromagnetic Induction. EMF Induced in a Moving Conductor
Topics Chapter 22 Electromagnetic Induction EMF Induced in a Moving Conductor Magnetic Flux EMF Induced in a Moving Conductor Demo: Solenoid and Magnet v 1 EMF Induced in a Moving Conductor q Work done
More informationChapter 23 Magnetic Flux and Faraday s Law of Induction
Chapter 23 Magnetic Flux and Faraday s Law of Induction Recall: right hand rule 2 10/28/2013 Units of Chapter 23 Induced Electromotive Force Magnetic Flux Faraday s Law of Induction Lenz s Law Mechanical
More informationLast time. Gauss' Law: Examples (Ampere's Law)
Last time Gauss' Law: Examples (Ampere's Law) 1 Ampere s Law in Magnetostatics iot-savart s Law can be used to derive another relation: Ampere s Law The path integral of the dot product of magnetic field
More informationK2-04: FARADAY'S EXPERIMENT - EME K2-43: LENZ'S LAW - PERMANENT MAGNET AND COILS
K2-04: FARADAY'S EXPERIMENT - EME SET - 20, 40, 80 TURN COILS K2-62: CAN SMASHER - ELECTROMAGNETIC K2-43: LENZ'S LAW - PERMANENT MAGNET AND COILS K2-44: EDDY CURRENT PENDULUM K4-06: MAGNETOELECTRIC GENERATOR
More informationChapter 12. Magnetism and Electromagnetism
Chapter 12 Magnetism and Electromagnetism 167 168 AP Physics Multiple Choice Practice Magnetism and Electromagnetism SECTION A Magnetostatics 1. Four infinitely long wires are arranged as shown in the
More informationPHYSICS. Chapter 30 Lecture FOR SCIENTISTS AND ENGINEERS A STRATEGIC APPROACH 4/E RANDALL D. KNIGHT
PHYSICS FOR SCIENTISTS AND ENGINEERS A STRATEGIC APPROACH 4/E Chapter 30 Lecture RANDALL D. KNIGHT Chapter 30 Electromagnetic Induction IN THIS CHAPTER, you will learn what electromagnetic induction is
More informationInduced Electric Field
Lecture 18 Chapter 33 Physics II Induced Electric Field Course website: http://faculty.uml.edu/andriy_danylov/teaching/physicsii Applications of Faraday s Law (some leftovers from the previous class) Applications
More informationPHYS102 Previous Exam Problems. Induction
PHYS102 Previous Exam Problems CHAPTER 30 Induction Magnetic flux Induced emf (Faraday s law) Lenz law Motional emf 1. A circuit is pulled to the right at constant speed in a uniform magnetic field with
More informationCHAPTER 5 ELECTROMAGNETIC INDUCTION
CHAPTER 5 ELECTROMAGNETIC INDUCTION 1 Quick Summary on Previous Concepts Electrostatics Magnetostatics Electromagnetic Induction 2 Cases of Changing Magnetic Field Changing Field Strength in a Loop A Loop
More informationMagnetic Induction Faraday, Lenz, Mutual & Self Inductance Maxwell s Eqns, E-M waves. Reading Journals for Tuesday from table(s)
PHYS 2015 -- Week 12 Magnetic Induction Faraday, Lenz, Mutual & Self Inductance Maxwell s Eqns, E-M waves Reading Journals for Tuesday from table(s) WebAssign due Friday night For exclusive use in PHYS
More informationChapter 5. Electromagnetic Induction
Chapter 5 Electromagnetic Induction Overview In the last chapter, we studied how a current produces a magnetic field. Here we will study the reverse effect: A magnetic field can produce an electric field
More informationFaraday s Law. Faraday s Law of Induction Motional emf. Lenz s Law. Motors and Generators. Eddy Currents
Faraday s Law Faraday s Law of Induction Motional emf Motors and Generators Lenz s Law Eddy Currents Induced EMF A current flows through the loop when a magnet is moved near it, without any batteries!
More informationChapter 7. Electrodynamics
Chapter 7. Electrodynamics 7.2 Electromagnetic Induction 7.2.1 Faraday's Law In 1831 Michael Faraday reported on a series of experiments: Experiment 1. He pulled a loop of wire to the right through a magnetic
More informationPHYS 1442 Section 004 Lecture #14
PHYS 144 Section 004 Lecture #14 Wednesday March 5, 014 Dr. Chapter 1 Induced emf Faraday s Law Lenz Law Generator 3/5/014 1 Announcements After class pickup test if you didn t Spring break Mar 10-14 HW7
More informationIntroduction. First Experiment
Course : Bsc Applied Physical Science(Computer Science) IInd Year (Semester IV) Paper no : 14 Paper title : Electromagnetic Theory Lecture No : 14 Tittle : Faraday s Law of Induction Introduction Hello
More informationInduction and Inductance
Induction and Inductance Key Contents Faraday s law: induced emf Induction and energy transfer Inductors and inductance RL circuits Magnetic energy density The First Experiment 1. A current appears only
More informationSlide 1 / 24. Electromagnetic Induction 2011 by Bryan Pflueger
Slide 1 / 24 Electromagnetic Induction 2011 by Bryan Pflueger Slide 2 / 24 Induced Currents If we have a galvanometer attached to a coil of wire we can induce a current simply by changing the magnetic
More informationCHAPTER 5: ELECTROMAGNETIC INDUCTION
CHAPTER 5: ELECTROMAGNETIC INDUCTION PSPM II 2005/2006 NO. 5 5. An AC generator consists a coil of 30 turns with cross sectional area 0.05 m 2 and resistance 100 Ω. The coil rotates in a magnetic field
More informationDavid J. Starling Penn State Hazleton PHYS 212
and and The term inductance was coined by Oliver Heaviside in February 1886. David J. Starling Penn State Hazleton PHYS 212 and We have seen electric flux: Φ E = E d A But we can define the magnetic flux
More informationPhysics for Scientists & Engineers 2
Induction Physics for Scientists & Engineers 2 Spring Semester 2005 Lecture 25! Last week we learned that a current-carrying loop in a magnetic field experiences a torque! If we start with a loop with
More informationHomework due next Tuesday 11:59 PM Next Sunday: no in-person office hour (try a skype office hour 7:45 8:15?)
Homework due next Tuesday 11:59 PM Next Sunday: no in-person office hour (try a skype office hour 7:45 8:15?) SUNDAY Nov 18: SECOND HOUR EXAM 6:10-7:30 PM in SEC 111 (Ch. 26-30) -- no recitations the previous
More informationPH 1120: Summary Homework 4 Solutions
PH 112: Summary Homework Solutions Term B8 1.(a) The path of the ion is a semicircle curving to the right from the point of entry, and terminating at the point X on the plate. (b) From the right hand rule,
More informationPhysics Notes for Class 12 chapter 6 ELECTROMAGNETIC I NDUCTION
1 P a g e Physics Notes for Class 12 chapter 6 ELECTROMAGNETIC I NDUCTION Whenever the magnetic flux linked with an electric circuit changes, an emf is induced in the circuit. This phenomenon is called
More informationPhysics 11b Lecture #13
Physics 11b Lecture #13 Faraday s Law S&J Chapter 31 Midterm #2 Midterm #2 will be on April 7th by popular vote Covers lectures #8 through #14 inclusive Textbook chapters from 27 up to 32.4 There will
More informationMagnetic inductance & Solenoids. P.Ravindran, PHY041: Electricity & Magnetism 22 February 2013: Magnetic inductance, and Solenoid
Magnetic inductance & Solenoids Changing Magnetic Flux A changing magnetic flux in a wire loop induces an electric current. The induced current is always in a direction that opposes the change in flux.
More informationPHY 1214 General Physics II
PHY 1214 General Physics II Lecture 19 Induced EMF and Motional EMF July 5-6, 2005 Weldon J. Wilson Professor of Physics & Engineering Howell Hall 221H wwilson@ucok.edu Lecture Schedule (Weeks 4-6) We
More informationProblem Solving: Faraday s Law & Inductance. Faraday s Law
MASSACHUSETTS INSTITUTE OF TECHNOLOGY Department of Physics: 8.02 Problem Solving: Faraday s Law & Inductance Section Table Names Faraday s Law In Chapter 10 of the 8.02 Course Notes, we have seen that
More informationMagnetism. and its applications
Magnetism and its applications Laws of Magnetism 1) Like magnetic poles repel, and 2) unlike poles attract. Magnetic Direction and Strength Law 3 - Magnetic force, either attractive or repelling varies
More informationELECTROMAGNETIC INDUCTION AND FARADAY S LAW
ELECTROMAGNETIC INDUCTION AND FARADAY S LAW Magnetic Flux The emf is actually induced by a change in the quantity called the magnetic flux rather than simply py by a change in the magnetic field Magnetic
More informationInduced Electric Field
Lecture 20 Chapter 30 Induced Electric Field This fool said some nonsense that the electric field can be produced from the magnetic field. Course website: http://faculty.uml.edu/andriy_danylov/teaching/physicsii
More informationSlide 1 / 50. Electromagnetic Induction and Faraday s Law
Slide 1 / 50 Electromagnetic Induction and Faraday s Law Slide 2 / 50 Electromagnetic Induction and Faraday s Law Induced EMF Faraday s Law of Induction Lenz s Law EMF Induced in a Moving Conductor Changing
More informationDO PHYSICS ONLINE MOTORS AND GENERATORS FARADAY S LAW ELECTROMAGNETIC INDUCTION
DO PHYSICS ONLINE MOTORS AND GENERATORS FARADAY S LAW ELECTROMAGNETIC INDUCTION English Michael Faraday (1791 1867) who experimented with electric and magnetic phenomena discovered that a changing magnetic
More informationGeneral Physics - E&M (PHY 1308) - Lecture Notes. General Physics - E&M (PHY 1308) Lecture Notes
General Physics - E&M (PHY 1308) Lecture Notes Lecture 029: Forms of Induction and Self-Inductance SteveSekula, 8 November 2010 (created 7 November 2010) Goals of this Lecture no tags Further understand
More informationInduced Electric Field
Lecture 18 Chapter 30 Physics II Induced Electric Field Course website: http://faculty.uml.edu/andriy_danylov/teaching/physicsii Today we are going to discuss: Chapter 30: Section 30.5, 30.6 Section 30.7
More informationElectromagnetic Induction and Faraday s Law
Electromagnetic Induction and Faraday s Law Induced EMF Almost 200 years ago, Faraday looked for evidence that a magnetic field would induce an electric current with this apparatus: He found no evidence
More informationPhysics 115. Induction Induced currents. General Physics II. Session 30
Physics 115 General Physics II Session 30 Induction Induced currents R. J. Wilkes Email: phy115a@u.washington.edu Home page: http://courses.washington.edu/phy115a/ 1 Lecture Schedule Today 5/23/14 2 Physics
More informationRevision Guide for Chapter 15
Revision Guide for Chapter 15 Contents Revision Checklist Revision otes Transformer...4 Electromagnetic induction...4 Lenz's law...5 Generator...6 Electric motor...7 Magnetic field...9 Magnetic flux...
More information(a) zero. B 2 l 2. (c) (b)
1. Two identical co-axial circular loops carry equal currents circulating in the same direction: (a) The current in each coil decrease as the coils approach each other. (b) The current in each coil increase
More informationPhysics 132: Lecture 15 Elements of Physics II Agenda for Today
Physics 132: Lecture 15 Elements of Physics II Agenda for Today Lenz Law Emf opposes change in flux Faraday s Law Induced EMF in a conducting loop Physics 132: Lecture 15, Pg 1 Lenz s Law Physics 132:
More informationElectromagnetic Induction
Electromagnetic Induction PHY232 Remco Zegers zegers@nscl.msu.edu Room W109 cyclotron building http://www.nscl.msu.edu/~zegers/phy232.html previously: electric currents generate magnetic field. If a current
More informationPHY 131 Review Session Fall 2015 PART 1:
PHY 131 Review Session Fall 2015 PART 1: 1. Consider the electric field from a point charge. As you move farther away from the point charge, the electric field decreases at a rate of 1/r 2 with r being
More informationOutside the solenoid, the field lines are spread apart, and at any given distance from the axis, the field is weak.
Applications of Ampere s Law continued. 2. Field of a solenoid. A solenoid can have many (thousands) of turns, and perhaps many layers of windings. The figure shows a simple solenoid with just a few windings
More informationPHY 1214 General Physics II
PHY 1214 General Physics II Lecture 20 Magnetic Flux and Faraday s Law July 6-7, 2005 Weldon J. Wilson Professor of Physics & Engineering Howell Hall 221H wwilson@ucok.edu Lecture Schedule (Weeks 4-6)
More informationApplication Of Faraday s Law
Application Of Faraday s Law Dr Miguel Cavero September 2, 2014 Application Of Faraday s Law September 2, 2014 1 / 23 The PHYS120 Exam will be divided into three sections as follows: Section A: Short Questions
More informationmag ( ) 1 ). Since I m interested in the magnitude of the flux, I ll avoid the minus sign by taking the normal to point upward.
hysics 40 Homework olutions - Walker Chapter 3 Conceptual Questions CQ5. Before the switch is closed there is no current in the coil and therefore no netic flux through the metal ring. When the switch
More informationAP Physics C - E & M
AP Physics C - E & M Electromagnetic Induction 2017-07-14 www.njctl.org Table of Contents: Electromagnetic Induction Click on the topic to go to that section. Induced EMF Magnetic Flux and Gauss's Law
More informationQuestion 6.1: Predict the direction of induced current in the situations described by the following Figs. 6.18(a) to (f ). (a) (b) (c) (d) (e) (f) The direction of the induced current in a closed loop
More informationCan a Magnetic Field Produce a Current?
Can a Magnetic Field Produce a Current? In our study of magnetism we learned that an electric current through a wire, or moving electrically charged objects, produces a magnetic field. Could the reverse
More informationAgenda for Today. Elements of Physics II. Lenz Law. Emf opposes change in flux Faraday s Law Induced EMF in a conducting loop
Lenz Law Physics 132: Lecture e 22 Elements of Physics II Agenda for Today Emf opposes change in flux Faraday s Law Induced EMF in a conducting loop Physics 201: Lecture 1, Pg 1 Lenz s Law Physics 201:
More informationFaraday s Law. Lecture 17. Chapter 33. Physics II. Course website:
Lecture 17 Chapter 33 Physics II Faraday s Law Course website: http://faculty.uml.edu/andriy_danylov/teaching/physicsii Lecture Capture: http://echo360.uml.edu/danylov201415/physics2spring.html Electromagnetic
More informationFaraday s Law. Lecture 17. Chapter 33. Physics II. Course website:
Lecture 17 Chapter 33 Physics II Faraday s Law Course website: http://faculty.uml.edu/andriy_danylov/teaching/physicsii Electromagnetic induction We saw that a magnetic field could be produced with an
More information