# Chapter 5: Electromagnetic Induction

Size: px
Start display at page:

Transcription

1 Chapter 5: Electromagnetic Induction 5.1 Magnetic Flux Define and use magnetic flux Magnetic flux is defined as the scalar product between the magnetic flux density, B with the vector of the area, A. It is a measure of the number of magnetic field lines that cross a given area. Mathematically, B A BAcos It is a scalar quantity. Unit SI for Φ is T m or Wb ( weber ) where Ф is magnetic flux θ is the angle between and If the coil is composed of N turns, all of the same area A, thus the magnetic flux through N turns coil (magnetic flux linkage) is: Note: NBAcos Direction of vector A always perpendicular (normal) to the surface area, A. The magnetic flux is proportional to the number of field lines passing through the area. Example A single turn of rectangular coil of sides 10 cm 5.0 cm is placed between north and south poles of a permanent magnet. Initially, the plane of the coil is parallel to the magnetic field as shown in Figure. Solution If the coil is turned by 90 about its rotation axis and the magnitude of magnetic flux density is 1.5T, calculate the change in the magnetic flux through coil. BP3 1 FYSL

2 5. Induced emf Electromagnetic induction is the production of an induced e.m.f. (or voltage) across a conductor or circuit situated in a changing magnetic field. The meaning of changing in magnetic flux: There is a relative motion of loop & magnet field lines are cut : The number of magnetic field lines passing through a coil are increased or decreased: 5..1 Use Faraday s experiment to explain induced emf Faraday s Experiment When there is no relative motion between the magnet & the loop, G shows no deflection. No induced current. Moving the magnet toward the loop increases the number of magnetic field lines passing through loop. The G needle is deflected indicating an induced current is produced. Moving the magnet away from the loop decreases the number of magnetic field lines passing through the loop. The induced current is now in opposite direction. Conclusion: From the experiments, it can be seen that e.m.f is induced only when the magnetic flux through the coil change. BP3 FYSL

3 The magnitude of induced e.m.f. can be increased by: Increasing the number of turns, N Increasing the strength of magnet/ use stronger magnet (magnetic flux increased), B Increasing the area of the coil or solenoid, A Move the magnet into or out the solenoid faster 5.. State Faraday s law and use Lenz s law to determine the direction of induced current Faraday s law of induction states that the magnitude of the induced e.m.f. is proportional to the rate of change of the magnetic flux. Mathematically, d where dф is change of magnetic flux is change of time The negative sign indicates that the direction of induced e.m.f. always oppose the change of magnetic flux producing it (Lenz s law). (To calculate the magnitude of induced e.m.f., the negative sign can be ignored.) Lenz s law states that an induced current always flow in a direction that opposes the change in magnetic flux that causes it. By Lenz s Law, when magnet is inserted into the solenoid, a North pole will be induced on the right side of coil to oppose the incoming North pole. By right hand grip rule, the induced current will flow anticlockwise so that pointer deflects to right. By Lenz s Law, when magnet is withdrawn from the solenoid, a South pole will be induced on the right side of coil to oppose the outgoing North pole. By right hand grip rule, the induced current will flow clockwise so that pointer deflects to left Lenz s Law is an example of principle of Conservation of Energy. Mechanical work is done to against the opposing magnetic force experienced by the moving magnet, and this work is converted into electrical energy as indicated by induced current flowing in the circuit. Faraday s Law gives the magnitude of induced e.m.f. while Lenz s Law gives the direction of the induced e.m.f.. BP3 3 FYSL

4 Example The solenoid in figure is moved at constant velocity towards a fixed bar magnet. Using Lenz s law, determine the direction of the induced current through the resistor. Solution Figure shows a permanent magnet approaching a loop of wire. The external circuit attached to the loop consists of the resistance R. Find the direction of the induced current and the polarity of the induced e.m.f.. Exercise A bar magnet is held above a loop of wire in a horizontal plane, as shown in figure. The south end of the magnet is toward the loop of the wire. The magnet is dropped toward the loop. Find the direction of the current through the resistor a. while the magnet falling toward the loop and b. after the magnet has passed through the loop and moves away from it. BP3 4 FYSL

5 d 5..3 Use induced emf 5..4 Derive and use induced e.m.f. in straight conductor/ in coil/ in rotating coil d According to Faraday s law, the magnitude of induced e.m.f. is given by CASE 1: Induced e.m.f. in a straight conductor Consider a linear (straight) conductor PQ of length l is moved perpendicular with velocity v across a uniform magnetic field B. When the conductor moved through a distance x in time t, the area swept out by the conductor is given by BAcos Blx d dblx dx Bl Blv and θ = 0 and In general, the magnitude of the induced e.m.f. in a linear conductor is given by vbl sin where θ is the angle between v and B In vector form, d v Bd l ε The direction of induced e.m.f. can be determined by using right hand rule. Thumb induced e.m.f./ induced current Other fingers direction of motion Palm magnetic flux v B BP3 5 FYSL

6 CASE : Induced e.m.f. in coil Figure shows a coil of N turns each of area A in a magnetic flux density B. Since, an e.m.f. can be induced in three ways: 1. by changing the magnetic flux density B. by changing the area A of the loop in the field 3. by changing the orientation θ with respect to the field (rotating coil) By changing the magnetic flux density B For a coil of N turns: By changing the area A For a coil of N turns: d N and BAcos d N and BAcos d BAcos N By changing the magnetic flux density B d BAcos N By changing the area A of the loop in uniform magnetic field NA cos db If B is perpendicular to the plane of coil θ = 0 NA db NB cos da If B is perpendicular to the plane of coil θ = 0 NB da For a coil is connected in series to a resistor of resistance R and the induced emf exist in the coil as shown in figure. d N and IR d IR N BP3 6 FYSL

7 CASE 3: Induced e.m.f. in a rotating coil As a coil rotates in a uniform magnetic field, the magnetic flux through the area enclosed by the coil changes with time; therefore induces an e.m.f. & current in the coil according to Faraday s Law. From: Φ = NBA cos θ As coil rotates, θ change, flux changes cos θ, Φ Flux changes induces an emf or current Suppose that, coil has N turns, all of the same area A & rotates in a magnetic field B with a constant angular velocity ω: d N d BAcos N BAcos d NAB cos and θ = ωt in rotational motion NAB d and cost NAB sint The magnitude of the e.m.f induced in rotating coil is given by: NAB sint or NAB sin Coil perpendicular with B θ = 0 ε min = 0 Coil parallel with B θ = 90 ε max = NABω BP3 7 FYSL

8 Example A 0 cm long metal rod CD is moved at speed of 5 m s -1 across a uniform magnetic field of flux density 50 mt. The motion of the rod is perpendicular to the magnetic field as shown in figure below. Solution a) Calculate the motional induced e.m.f. in the rod. b) If the rod is connected in series to the resistor of resistance 15 Ω, determine i. the induced current and its direction. ii. the total charge passing through the resistor in two minute. A single turn circular shaped coil has resistance of 10 Ω and area of its plane is 5.0 cm. It moves towards the north pole of a bar magnet as shown in figure below. If the average rate of change of magnetic flux density through the plane of the coil is 0.50 T s -1, determine the induced current in the coil and state the direction of the induced current observed by the observer shown in figure above. A narrow coil of 10 turns and diameter of 4.0 cm is placed perpendicular to a uniform magnetic field of 1.0 T. After 0.5 s, the diameter of the coil is increased to 5.3 cm. a. Calculate the change in the area of the coil. b. If the coil has a resistance of.4 Ω, determine the induced current in the coil. BP3 8 FYSL

10 5.3 Self-inductance Self-induction is defined as the process of producing an induced e.m.f. in the coil due to a change of current flowing through the same coil. I I When the switch is closed, a current begin to flow in the solenoid. The current produces a magnetic field lines through the solenoid and generate the magnetic flux linkage. If the resistance of the variable resistor changes, thus the current flows in the solenoid also changed, then so does the magnetic flus linkage. According to Faraday s law, an e.m.f has to be induced in the solenoid itself since the flux linkage changes. In accordance to the Lenz s law, the induced e.m.f opposes the change that has induced it and it is therefore known as back e.m.f. I increases I decreases S N N S ε induced ε induced N S N S If the current is increasing, so is the magnetic flux. According to the Lenz s law, the induced e.m.f. acts to oppose the increasing flux, which means it acts like a source of e.m.f. that opposes the external e.m.f.. This induced e.m.f. is also known as back e.m.f.. Therefore the direction of the induced e.m.f is in the opposite direction of the current I. If the current is decreasing, so is the magnetic flux. According to the Lemz s law, the induced e.m.f. acts to oppose the decreaseing flux, which means it acts to bolster the flux, like a source of e.m.f. reinforcing the external e.m.f.. Therefore the direction of the induced e.m.f is in the same direction of the current I. BP3 10 FYSL

11 5.3.1 Define self-inductance 5.3. Apply self-inductance equation for coil and solenoid From the process of self-induction, we know that magnetic field B is proportional to current I, and magnetic flux Ф is proportional to magnetic field B. Therefore Mathematically, I LI Self-inductance L is defined as the ratio set induced e.m.f. to the rate change current in the coil. L It is a scalar quantity and its unit is henry (H). di Unit conversion: 1 H 1 Wb A 1 1 T m A 1 For N turns of coil: Magnetic flux linkage N LI L N I 0 N r A For N turns of solenoid: L N I 0 N l A The value of the self-inductance depends on the size and shape of the coil, the number of turn (N), the permeability of the medium in the coil (). A circuit element which possesses mainly self-inductance is known as an inductor. It is used to store energy in the form of magnetic field. The symbol of inductor: BP3 11 FYSL

12 Example At an instant, the current in an inductor increases at the rate of 0.06 A s -1 and back e.m.f. of V was produced in the inductor. a. Calculate the self-inductance of the inductor. b. If the inductor is a solenoid with 300 turns, find the magnetic flux through each turn when the current of 0.80 A flows in it. Solution A 500 turns of solenoid is 8.0 cm long. When the current in the solenoid is increased from 0 to.5 A in 0.35 s, the magnitude of the induced e.m.f. is 0.01 V. Calculate a. the inductance of the solenoid, b. the cross-sectional area of the solenoid, c. the final magnetic flux linkage through the solenoid. (Given µ 0 = 4p 10-7 H m -1 ) Exercise The coil in an electromagnet has an inductance of 1.7 mh and carries a constant direct current of 5.6 A. A switch is suddenly opened, allowing the current to drops to zero over a small interval of time, t. If the magnitude of the e.m.f. induced during this time is 7.3 V, what is t? Answer: 1.3 ms A 500 turns solenoid is 8.0 cm long. When the current in this solenoid is increased from 0 to 0.5 A in 0.35 s the magnitude of the induced e.m.f. is 0.01 V. Find a. the inductance and b. the cross sectional area of the solenoid. Answer: 1.7 mh; m A 40.0 ma current is carried by a uniformly wound air-core solenoid with 450 turns, a 15.0 mm diameter and 1.0 cm length. Calculate a. the magnetic field inside the solenoid, b. the magnetic flux through each turn, c. the inductance of the solenoid. Answer: T; Wb; H BP3 1 FYSL

13 5.4 Energy stored in inductor Derive and use the energy stored in an inductor Consider a coil of self-inductance L. Suppose that at time t the current in the coil is in the process of building up to its stable value I at a rate di/. The magnitude of the back e.m.f. ε is given by di L The power P in overcoming this back e.m.f. is given by P I Power time = Energy di P IL P ILdI du ILdI du L I 0 IdI 1 U LI Example An 8.0 cm long solenoid with an air-core consists of 100 turns of diameter 1. cm. If the current flows in it is 0.77 A, determine a. the self-inductance of the coil b. the energy stored in the coil (Given µ 0 = 4π x 10-7 H m -1 ) Solution Exercise At the instant when the current in an inductor is increasing at a rate of A s -1, the magnitude of the back e.m.f. is 0.016V. a) Calculate the inductance of the inductor. b) If the inductor is a solenoid with 400 turns and the current flows in is 0.70 A, determine i. the magnetic flux through each turn ii. the energy stored in the solenoid. Answer: 0.5 H; Wb, J BP3 13 FYSL

14 5.5 Mutual-inductance Mutual induction is defined as the process of producing an induced e.m.f in one coil due to the change of current in another coil. Primary coil Secondary coil Consider two circular close-packed coils near each other and sharing a common central axis as shown in figure. A current I 1 flows in coil 1, produced by the battery in the external circuit. The current I 1 produces a magnetic field lines inside it and this field lines also pass through coil as shown in figure. If the current I 1 changes with time, the magnetic flux through coils 1 and will change with time simultaneously. Due to the change of magnetic flux through coil, an e.m.f. is induced in coil. This is in accordance to the Faraday s law of induction. In other words, a change of current in one coil leads to the production of an induced e.m.f. in a second coil which is magnetically linked to the first coil. According to Lenz s law, the induced current produced in coil will oppose the change in I 1. This process is known as mutual induction. At the same time, the self-induction occurs in coil 1 since the magnetic flux through it changes. S N S N S N N S BP3 14 FYSL

15 5.5.1 Define mutual inductance 5.5. Use mutual inductance question between two coaxial solenoids or a coaxial coil and solenoid If the current I 1 in coil 1 is changes, the magnetic flux B through coil will change with time t and an induced e.m.f ε will occur in coil where Mathematically, Lenz s law di 1 M 1 di1 If vice versa, the induced e.m.f. in coil 1, ε 1 is given by Conclusion, 1 M 1 di M 1 M 1 M Mutual inductance is defined as the ratio of induced e.m.f in a coil to the rate of change of current in another coil. For a given pair of coils, the value of mutual inductance is the same and does not depend on which coil carries the current and which coil experiences induction. For N turns of coil: M 1 N I or 1 M 1 N1 I 1 Mutual inductance between two coaxial solenoids or a coaxial coil and solenoid M 0 N1N A l N 1 : primary coil N : secondary coil BP3 15 FYSL

16 Example A current of.0 A flows in coil P and produced a magnetic flux of 0.6 Wb in it. When a coil S is moved near to coil P coaxially, a flux of 0. Wb is produced in coil S. Given that, coil P has 100 turns and coil S has 00 turns. a. Calculate self-inductance of coil P and the energy stored in P before S is moved near to it. b. Calculate the mutual inductance of the coils. c. If the current in P decreasing uniformly from.0 A to zero in 0.4 s, calculate the induced e.m.f. in coil S. Solution Primary coil of a cylindrical former with the length of 50 cm and diameter 3 cm has 1000 turns. If the secondary coil has 50 turns, calculate : a. its mutual inductance b. the induced e.m.f. in the secondary coil if the current flowing in the primary coil is changing at the rate of 4.8 A s -1. Exercise Two coils, X and Y are magnetically coupled. The e.m.f. induced in coil Y is.5 V when the current flowing through coil X changes at the rate of 5 A s -1. Determine: a. the mutual inductance of the coils b. the e.m.f. induced in coil X if there is a current flowing through coil Y which changes at the rate of 1.5 A s -1. Answer : 0.5 H ; 0.75 V Two coils, X and Y have mutual inductance of 550 mh. Determine the rate of change of magnetic flux through coil Y at the instant when the current flowing through coil X changes at the rate of 5.5 A s -1. Given that, both coil X and Y has 100 turns. Answer: Wb s -1 BP3 16 FYSL

### Physics 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

### CHAPTER 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

### ELECTROMAGNETIC 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

### Chapter 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

### Chapter 31. Faraday s Law

Chapter 31 Faraday s Law 1 Ampere s law Magnetic field is produced by time variation of electric field dφ B ( I I ) E d s = µ o + d = µ o I+ µ oεo ds E B 2 Induction A loop of wire is connected to a sensitive

### Demo: 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

### Chapter 31. Faraday s Law

Chapter 31 Faraday s Law 1 Ampere s law Magnetic field is produced by time variation of electric field B s II I d d μ o d μo με o o E ds E B Induction A loop of wire is connected to a sensitive ammeter

### Chapter 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

Question 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

### Chapter 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

### FARADAY 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

### Electromagnetic Induction (Chapters 31-32)

Electromagnetic Induction (Chapters 31-3) The laws of emf induction: Faraday s and Lenz s laws Inductance Mutual inductance M Self inductance L. Inductors Magnetic field energy Simple inductive circuits

### Ch. 23 Electromagnetic Induction, AC Circuits, And Electrical Technologies

Ch. 23 Electromagnetic Induction, AC Circuits, And Electrical Technologies Induced emf - Faraday s Experiment When a magnet moves toward a loop of wire, the ammeter shows the presence of a current When

### Chapter 30. Induction and Inductance

Chapter 30 Induction and Inductance 30.2: First Experiment: 1. A current appears only if there is relative motion between the loop and the magnet (one must move relative to the other); the current disappears

### Electromagnetic 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.

### PHYS102 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

### Chapter 30. Induction and Inductance

Chapter 30 Induction and Inductance 30.2: First Experiment: 1. A current appears only if there is relative motion between the loop and the magnet (one must move relative to the other); the current disappears

### Chapter 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,

### Induction_P1. 1. [1 mark]

Induction_P1 1. [1 mark] Two identical circular coils are placed one below the other so that their planes are both horizontal. The top coil is connected to a cell and a switch. The switch is closed and

### Induction 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

### Revision 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...

### PHYSICS 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

### Chapter 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

### Magnets. 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

### Chapter 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

### FXA 2008 Φ = BA. Candidates should be able to : Define magnetic flux. Define the weber (Wb). Select and use the equation for magnetic flux :

1 Candidates should be able to : Define magnetic flux. Define the weber (Wb). Select and use the equation for magnetic flux : Φ = BAcosθ MAGNETIC FLUX (Φ) As we have already stated, a magnetic field is

### Handout 10: Inductance. Self-Inductance and inductors

1 Handout 10: Inductance Self-Inductance and inductors In Fig. 1, electric current is present in an isolate circuit, setting up magnetic field that causes a magnetic flux through the circuit itself. This

### LECTURE 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

### Slide 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

### Induction 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

### Sliding 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

### 21 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

### Chapters 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

### PHYS 241 EXAM #2 November 9, 2006

1. ( 5 points) A resistance R and a 3.9 H inductance are in series across a 60 Hz AC voltage. The voltage across the resistor is 23 V and the voltage across the inductor is 35 V. Assume that all voltages

### (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

### Revision 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

### Chapter 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

### Application 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

### Chapter 32. Inductance

Chapter 32 Inductance Joseph Henry 1797 1878 American physicist First director of the Smithsonian Improved design of electromagnet Constructed one of the first motors Discovered self-inductance Unit of

### Chapter 23: Magnetic Flux and Faraday s Law of Induction

Chapter 3: Magnetic Flux and Faraday s Law of Induction Answers Conceptual Questions 6. Nothing. In this case, the break prevents a current from circulating around the ring. This, in turn, prevents the

### CURRENT-CARRYING CONDUCTORS / MOVING CHARGES / CHARGED PARTICLES IN CIRCULAR ORBITS

PHYSICS A2 UNIT 4 SECTION 4: MAGNETIC FIELDS CURRENT-CARRYING CONDUCTORS / MOVING CHARGES / CHARGED PARTICLES IN CIRCULAR ORBITS # Questions MAGNETIC FLUX DENSITY 1 What is a magnetic field? A region in

### Electromagnetic 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

### Physics 1302W.400 Lecture 33 Introductory Physics for Scientists and Engineering II

Physics 1302W.400 Lecture 33 Introductory Physics for Scientists and Engineering II In today s lecture, we will discuss generators and motors. Slide 30-1 Announcement Quiz 4 will be next week. The Final

### Chapter 30. Inductance

Chapter 30 Inductance Self Inductance When a time dependent current passes through a coil, a changing magnetic flux is produced inside the coil and this in turn induces an emf in that same coil. This induced

### Self-inductance A time-varying current in a circuit produces an induced emf opposing the emf that initially set up the time-varying current.

Inductance Self-inductance A time-varying current in a circuit produces an induced emf opposing the emf that initially set up the time-varying current. Basis of the electrical circuit element called an

### Physics 106, Section 1

Physics 106, Section 1 Magleby Exam 2, Summer 2012 Exam Cid You are allowed a pencil and a testing center calculator. No scratch paper is allowed. Testing center calculators only. 1. A circular coil lays

### DEVIL PHYSICS THE BADDEST CLASS ON CAMPUS IB PHYSICS

DEVIL PHYSICS THE BADDEST CLASS ON CAMPUS IB PHYSICS TSOKOS LESSON 11-1 ELECTROMAGNETIC INDUCTION Essential Idea: The majority of electricity generated throughout the world is generated by machines that

### 18 - ELECTROMAGNETIC INDUCTION AND ALTERNATING CURRENTS ( Answers at the end of all questions ) Page 1

( Answers at the end of all questions ) Page ) The self inductance of the motor of an electric fan is 0 H. In order to impart maximum power at 50 Hz, it should be connected to a capacitance of 8 µ F (

### ENGINEERING COUNCIL CERTIFICATE LEVEL ENGINEERING SCIENCE C103 TUTORIAL 16 - INDUCTANCE

ENGINEERING COUNCIL CERTIFICATE LEVEL ENGINEERING SCIENCE C103 TUTORIAL 16 - INDUCTANCE On completion of this tutorial you should be able to do the following. Explain inductance and inductors. Explain

### INDUCTANCE Self Inductance

NDUTANE 3. Self nductance onsider the circuit shown in the Figure. When the switch is closed the current, and so the magnetic field, through the circuit increases from zero to a specific value. The increasing

### Physics / 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

### CHAPTER 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

### Physics 6B Summer 2007 Final

Physics 6B Summer 2007 Final Question 1 An electron passes through two rectangular regions that contain uniform magnetic fields, B 1 and B 2. The field B 1 is stronger than the field B 2. Each field fills

### University Physics Volume II Unit 2: Electricity and Magnetism Chapter 13: Electromagnetic Induction Conceptual Questions

University Physics Volume II Conceptual Questions 1. A stationary coil is in a magnetic field that is changing with time. Does the emf induced in the coil depend on the actual values of the magnetic field?

### Electromagnetic Induction Faraday s Law Lenz s Law Self-Inductance RL Circuits Energy in a Magnetic Field Mutual Inductance

Lesson 7 Electromagnetic Induction Faraday s Law Lenz s Law Self-Inductance RL Circuits Energy in a Magnetic Field Mutual Inductance Oscillations in an LC Circuit The RLC Circuit Alternating Current Electromagnetic

### Electromagnetic Induction

362 Mechanical Engineering Technician UNIT 7 Electromagnetic Induction Structure 7.1 Introduction 7.2 Faraday s laws of Electromagnetic Induction 7.3. Lenz s law 7.4. Fleming s right and rule 7.5. Self

### Magnetic Fields

Magnetic circuits introduction Becomes aware of the similarities between the analysis of magnetic circuits and electric circuits. Develop a clear understanding of the important parameters of a magnetic

### PHYS 202 Notes, Week 6

PHYS 202 Notes, Week 6 Greg Christian February 23 & 25, 2016 Last updated: 02/25/2016 at 12:36:40 This week we learn about electromagnetic induction. Magnetic Induction This section deals with magnetic

### Lecture 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

### Slide 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

### Slide 1 / 50. Slide 2 / 50. Slide 3 / 50. Electromagnetic Induction and Faraday s Law. Electromagnetic Induction and Faraday s Law.

Electromagnetic Induction and Faraday s Law Slide 1 / 50 Electromagnetic Induction and Faraday s Law Slide 2 / 50 Induced EMF Faraday s Law of Induction Lenz s Law EMF Induced in a Moving Conductor Changing

### Induction 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:

### Lecture 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,

### Electromagnetic Induction & Inductors

Electromagnetic Induction & Inductors 1 Revision of Electromagnetic Induction and Inductors (Much of this material has come from Electrical & Electronic Principles & Technology by John Bird) Magnetic Field

### C. Incorrect! Use the formula for magnetic flux. This is the product of magnetic field, times area, times the angle between them.

AP Physics - Problem Drill 17: Electromagnetism Instruction: (1) Read the problem statement and answer choices carefully (2) Work the problems on paper as 1. A house has a wall that has an area of 28 m

### Version 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.

### PHYSICS. 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

### Chapter 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

### DO 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

### Chapter 22. Induction

Chapter 22 Induction Induced emf A current can be produced by a changing magnetic field First shown in an experiment by Michael Faraday A primary coil is connected to a battery A secondary coil is connected

### MAGNETISM. Magnet. When a piece of material is brought close to or stroked by a magnet, the material itself becomes magnetic.

1 MAGNETISM Magnet A magnet is any material that is able to attract iron or steel. Materials that are attracted to magnets are called ferromagnetic. (e.g. iron, steel, cobalt) When a piece of material

### Electricity & 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 =

### PHYSICS - 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

### Version The diagram below represents lines of magnetic flux within a region of space.

1. The diagram below represents lines of magnetic flux within a region of space. 5. The diagram below shows an electromagnet made from a nail, a coil of insulated wire, and a battery. The magnetic field

### r where the electric constant

1.0 ELECTROSTATICS At the end of this topic, students will be able to: 10 1.1 Coulomb s law a) Explain the concepts of electrons, protons, charged objects, charged up, gaining charge, losing charge, charging

### Module 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

### Physics 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

### Chapter 32. Inductance

Chapter 32 Inductance Inductance Self-inductance A time-varying current in a circuit produces an induced emf opposing the emf that initially set up the time-varying current. Basis of the electrical circuit

### Electrics. 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

### Calculus 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

### Last 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

### Physics 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

### PHY101: 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).

### Tactics: Evaluating line integrals

Tactics: Evaluating line integrals Ampère s law Whenever total current I through passes through an area bounded by a closed curve, the line integral of the magnetic field around the curve is given by Ampère

### PHY 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

### Magnetism. 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

### Faraday s Law of Electromagnetic Induction

Faraday s Law of Electromagnetic Induction 2.1 Represent and reason The rectangular loop with a resistor is pulled at constant velocity through a uniform external magnetic field that points into the paper

### Name: Class: Date: AP Physics Spring 2012 Q6 Practice. Multiple Choice Identify the choice that best completes the statement or answers the question.

ame: Class: Date: ID: A AP Physics Spring 2012 Q6 Practice Multiple Choice Identify the choice that best completes the statement or answers the question. 1. (2 points) A potential difference of 115 V across

### Unit 8: Electromagnetism

Multiple Choice Portion Unit 8: Electromagnetism 1. Four compasses are placed around a conductor carrying a current into the page, as shown below. Which compass correctly shows the direction of the magnetic

### Lecture 24. April 5 th, Magnetic Circuits & Inductance

Lecture 24 April 5 th, 2005 Magnetic Circuits & Inductance Reading: Boylestad s Circuit Analysis, 3 rd Canadian Edition Chapter 11.1-11.5, Pages 331-338 Chapter 12.1-12.4, Pages 341-349 Chapter 12.7-12.9,

### n Higher Physics 1B (Special) (PHYS1241) (6UOC) n Advanced Science n Double Degree (Science/Engineering) n Credit or higher in Physics 1A

Physics in Session 2: I n Physics / Higher Physics 1B (PHYS1221/1231) n Science, dvanced Science n Engineering: Electrical, Photovoltaic,Telecom n Double Degree: Science/Engineering n 6 UOC n Waves n Physical

### Chapter 23 Magnetic Flux and Faraday s Law of Induction

Chapter 23 Magnetic Flux and Faraday s Law of Induction 1 Overview of Chapter 23 Induced Electromotive Force Magnetic Flux Faraday s Law of Induction Lenz s Law Mechanical Work and Electrical Energy Generators

### a) head-on view b) side view c) side view Use the right hand rule for forces to confirm the direction of the force in each case.

Electromagnetism Magnetic Force on a Wire Magnetic Field around a Bar Magnet Direction of magnetic field lines: the direction that the North pole of a small test compass would point if placed in the field

### Revision Compare Between. Application

evision Compare etween Points of Comparison Series Connection Parallel Connection Drawing otal resistance ( ) = + + 3 3 Potential Difference () = + + 3 = = = 3 Electric Current (I) I = I = I = I 3 I =

### Magnetic 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

### 3/31/2014. Resistors in series. Resistors in parallel. Ohm s Law. Review for Test 2. Electric Power (cont d) V IR. R constant I

Ohm s Law eview for Test Ohm s law states that the current flowing through a piece of material is proportional to the voltage applied across the material. The resistance () is defined as the ratio of to.

### Electromagnetic 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,

### Electromagnetism IB 12

Electromagnetism Magnetic Field around a Bar Magnet Direction of magnetic field lines: the direction that the North pole of a small test compass would point if placed in the field (N to S) What is the