Design of english electronic lectures for teaching chapter electromagnetic induction, physics 11th grade.

THE UNIVERSITY OF DANANG UNIVERSITY OF EDUCATION FACULTY OF PHYSICS NGUYEN THI HONG CHI DESIGN OF ENGLISH ELECTRONIC LECTURES FOR TEACHING CHAPTER ELECTROMAGNETIC INDUCTION, BACHELOR

THE UNIVERSITY OF DANANG UNIVERSITY OF EDUCATION

FACULTY OF PHYSICS

NGUYEN THI HONG CHI

DESIGN OF ENGLISH ELECTRONIC LECTURES

FOR TEACHING CHAPTER ELECTROMAGNETIC INDUCTION,

BACHELOR THESIS

Da Nang, 2018

THE UNIVERSITY OF DANANG UNIVERSITY OF EDUCATION

FACULTY OF PHYSICS

NGUYEN THI HONG CHI

DESIGN OF ENGLISH ELECTRONIC LECTURES

FOR TEACHING CHAPTER ELECTROMAGNETIC INDUCTION,

ACKNOWLEDGEMENTS

In completion of my thesis, I have received generous advice and help from many people whose lectures are very practical and useful With deep respect and gratitude, I would like to express my sincere thanks to:

Teachers in the Faculty of Physics, University of Education - the University of

Da Nang has taught, helped me equip the necessary and precious knowledge

Dr Nguyen Quy Tuan who is my supervisor has guided and helped generously

me in the process of completing my thesis

Finally, I would like to thank my family, my friends, who always care and encourage me

Although, I have tried in the capacity and scope to allow myself to complete this thesis but not avoid the shortcomings.I hope to receive the sympathy and enthusiastic comments of teachers and friends

I sincerely thank!

Da Nang, April 2018 Student perform

NGUYEN THI HONG CHI

TABLE OF CONTENTS ACKNOWLEDGEMENTS I SYMBOL LISTS AND ACRONYMS IV LIST OF TABLES V LIST OF FIGURES V

INTRODUCTION 1

1 Rationale 1

2 Aims of the study 2

3 Research tasks 2

4 Subjects and scope of the study 2

5 Methods of study 2

CONTENTS 3

CHAPTER I: LITERATURE REVIEW AND PRACTICAL RESEARCH 3

1.1 Theoretical background of teaching the natural sciences subjects in English 3 1.1.1 Levels of teaching the natural sciences subjects in English 3

1.1.2 The roles of teaching the natural sciences subjects in English 3

1.2 Practical basis of teaching the natural sciences subjects in English 4

1.3.Electronic lecture 5

1.3.1 Electronic lecture concept 5

1.3.2 The roles of electronic lecture in teaching physics at high school 5

1.3.3 The process of design electronic lecture for teaching 6

1.3.4 Some notes for designing electronic lectures: 8

CHAPTER II: ENGLISH LESSON PLANS FOR TEACHING CHAPTER ELECTROMAGNETIC INDUCTION, PHYSIC 11 TH GRADE 10

2.1.Structural and content analysis of the “Electromagnetic induction”: 10

2.1.1 Features chapter: 10

2.1.2 Task of the chapter: 10

2.1.3 Schema logic content knowledge of the chapter: 11

2.1.4 Standard the knowledge, skills of the chapter “Electromagnetic induction” 11

2.2.Design the process of teaching electronic lecture in the chapter “Electromagnetic induction”: 12

2.2.1 Objectives: 12

2.2.2 Lesson structure: 12

2.2.3 Specific teaching process: 13

2.2.3.1 Magnetic flux Electromagnetic induction 13

2.2.3.2 The induced electromotive force 30

2.2.3.3 Self-induction 39

CHAPTER III: ELECTRONIC LECTURES ON CHAPTER “ELECTROMAGNETIC INDUCTION” PHYSIC 11 th GRADE 47

3.1.Some electronic lectures on chapter “Electromagnetic induction” Physic 11th grade 47

3.1.1 Magnetic flux Electromagnetic induction 47

3.1.2 The induced electromotive force 72

3.1.3 Self-induction 84

3.2.The rubric to evaluate the quality of electronic letures 93

CONCLUSION AND RECOMMENDATION 96

1 Conclusion: 96

2 Recommendation: 96

REFERENCES 98

SYMBOL LISTS AND ACRONYMS

LIST OF TABLES

1 Table 1 Standard of knowledge, skills of the

chapter “Electromagnetic induction”

11

LIST OF FIGURES

1 Figure 1 Schema logic content knowledge of

the chapter “Electromagnetic induction”

11

3 Figure 3 Cross work of “Magnetic flux

Electromagnetic induction”

20

Improving English language skills in English for high school students will help students improve their knowledge, research, make good use of opportunities and be able to think scientifically

Through advanced English teaching, the knowledge and teaching capacity of upper secondary school teachers are increasingly advanced, with access to the knowledge that advanced countries are teaching Therefore, the project “Teaching and learning foreign languages in the national education system in the period 2008 – 2020” was approved by the Prime Minister on 30/9/2013 This is to aim at comprehensively renovating the teaching and learning of foreign languages in the national education system, implementing new curricula and teaching programs at all levels It is expected that by 2015, a significant progress will be made in the level of proficiency in the use of foreign languages in human resources, especially in some priority areas By 2020, most of Vietnamese youths graduating from secondary schools, colleges and universities have the ability to speak foreign languages independently, confidently in communication, learning, working in an integrated, multilingual and multicultural environment; Foreigns languages become the strength of the Vietnamese people, serving the progress of industrialization and modernization of the country [9]

However, science teachers in general English and physics in particular are facing many difficulties, such as program-oriented issues, learning materials, methods and forms of organization To help teachers have an overview of materials search, composition, teaching and research for students, to effectively teach physics

in high school curricula in English

Starting from the above reasons, I chose the topic: “Design of English electronic lectures for teaching chapter “Electromagnetic induction”, Physics 11thgrade to research

2 Aims of the study

- Design of English electronic lectures for teaching chapter “Electromagnetic induction”, Physics 11th grade to develop foreign language skills for students

- Design of English lesson plans for teaching chapter “Electromagnetic induction”, Physics 11th grade

- Design study card and consolidation exercise

- Evaluate the quality of electronic lectures

3 Research tasks

- Research the theoretical and practical basis of the topic

- Design of English electronic lectures for teaching chapter “Electromagnetic induction”

4 Subjects and scope of the study

- The content of the chapter “Electromagnetic induction” in Physics 11th grade and similar content in English

- Research scope: Chapter “Electromagnetic induction” in Physics 11th grade

5 Methods of study

- Theoretical research method: Research related material to the topic

- Practical research methods: Rubric

- Consult expert

CONTENTS CHAPTER I: LITERATURE REVIEW AND PRACTICAL RESEARCH 1.1 Theoretical background of teaching the natural sciences subjects in

English

1.1.1 Levels of teaching the natural sciences subjects in English

Teaching science in English is beneficial to the development of the brain of students, helping them to have better memory, better concentration, and the ability

to get rid of irrelevant information Where English is not the mother tongue, teaching science in English is carried out gradually by three levels:

- Level 1: Teachers provide some Physics terms in English for students Then teachers teach in the classroom, communicate mainly in Vietnamese In this way, students will not be able to develop important skills in learning English, such as speaking, writing and communication skills

- Level 2: Bilingual teaching - simultaneous 50% English and 50% Vietnamese This approach is often used in complex situations, which are too new for students to catch up and fail to grasp the content of the problem

- Level 3: Teaching and organizing activities entirely in English.This method

is often used when the level of students is the same and the content is not too complicated but relatively familiar with the students By maximizing the use of this method, students will have the opportunity to improve their English language skills [2]

1.1.2 The roles of teaching the natural sciences subjects in English

English is an international language widely used in wide variety of fields including science, technology and education Therefore, English is a tool for us to access advanced education and modern science and technology Vietnam is a developing country and international integration which help us to improve the efficiency of education and training, exchange and apply advanced technologies in the world

Teaching physics and natural sciences in English at high school that is a strategic direction that will help solve the high demand for quality human resources

in the coming years [5]

1.2 Practical basis of teaching the natural sciences subjects in English

In the current socio-economic context, Vietnam is gradually integrating into the world In particular, the ASEAN Economic Community established on December 31st 2015, has brought more opportunities and challenges than ever for Vietnam in general and our country’s education in particular to train generations The youth have the ability to study and work in the international environment Therefore English plays an important role

Based on the results of the survey of 148 high school students in schools in Da Nang City with the theme "Students' interest in learning bilingual English-Vietnamese language", most of the students look forward to traveling and a small number of students preparing to study abroad in developed countries using English

as the United Kingdom, the United States Thus, teaching science in English is very necessary, helping students increasingly closer to the world science Most of the students now aware of English play a very important role since their English learning motivation are based on their own orientation

From the 2011 – 2012 school year, the teaching Math and the natural sciences subjects in English has been implemented in some high schools but it has some difficulties First, it is difficult for teachers:

Firstly, the capacity of foreign language teachers is still low, not meeting the demand for teaching bilingual teaching in schools Most teachers graduated from the majors in Vietnamese, new English skills Grade A, B, C according to Vietnamese standard or based on self-study and self-improvement The environment of foreign language interaction of teachers, many place almost no, so the deployment of bilingual teaching became a difficult problem, heavy with them Secondly, the level of English proficiency of students in rural, urban, and urban centers is uneven Not to mention pupils are children of border people, islands economic areas with special difficulties Not all children can pronounce the standard have a vocabulary, grammar rich to quickly access the lesson (while

English used in these lessons are specialized terminology) Guidance for children to adapt and adapt to this model also need time and longer route

Third, the standard textbook for bilingual teaching has not been officially issued The legal implications of bilingual teaching programs also make it hard to fathom as there are no specific guidelines from the Ministry of Education and Training Most teachers have to learn, study, consult other sources of information to develop the unit Besides, there are still mixed opinions in evaluating the quality of translation of textbooks for this work [4]

In recent years, there has been an urgent need for teaching science in English,

so some authors have studied the subject:

Pham Kim Chung has studied the topic: “Organizing the teaching of natural sciences in English for high school students” Presentation of the experimental results of Developing a teaching and learning plan for physics for the 10th grade students of the High School of Education Science in Hanoi in May 2017 with 26 English multiple choice questions The effectiveness of teaching CLIL helps students improve their ability to use English to study natural sciences; increase the excitement, promote the positive, active, improve the quality of teaching [3]

Physics Classes in bilingual English - Vietnamese Optical part, grade 11 Physics by Le Hang [11]; Design electronic lecture bilingual English-Vietnamese chapter “Direct current”, Physics 11th grade by Nguyen Thi Hop [4], etc

Teaching Physics in English A Continuing Professional Development for Native English-Speaking Teachers in Thailand by Chaninan Pruekpramool [8]

Non-1.3 Electronic lecture

1.3.1 Electronic lecture concept

Electronic lecture is a form of classroom-based programming in which all teaching plans are programmed by the teacher through a multimedia environment created by the computer [5]

1.3.2 The roles of electronic lecture in teaching physics at high school

The most convenient environment for conducting electronic lectures is the multimedia classroom equipped with computers, projectors, audio-visual

equipment Besides using modern teaching methods, it should be combined with traditional media such as blackboard, white powder There are many problems involved in calculating, so many teachers can write on the board so students can understand better When teaching by eLearning requires teachers to invest more But once it is put into use, the correction and addition will be easier, students are better known Students can be copied to install to the home for reference if the article is posted on the students, colleagues can refer to research, comments

Other way, Physics is an experimental science, so in teaching Physics, experimenting is a very important part that not only increases the attractiveness of the subject, but also helps students understand the deeply theory But more important is to give students a visual acumen However, in a class with limited time, experiment apparatus and experiments are difficult to observe with the naked eye, the use of virtual experiments, flash, video, images are integrated in the electronic lecture is very effective for teaching Physics in high school

Thus, electronic lecture has very important role in teaching Physics, providing knowledge and useful materials for teaching

1.3.3 The process of design English electronic lecture for teaching

Step 1 Determine the purpose and requirements of the electronic lecture

The goal here is the learning objective, not the instructional goal We are reading textbooks, incorporating local and foreign references to understand the content and purpose of each item in the lesson On that basis, determine the target of the whole lesson about knowledge, skills and attitudes That is the goal of the lesson

Step 2 Select basic knowledge, focus, generalization, and high filtering to

organize them into slides

This is an important step in expressing the whole contents of the lecture The contents of the slides should be really distilled from the basic knowledge of each chapter, item and paragraph The amount of information contained in a slide is not much, so the teacher must have synthesized and generalized thinking to select and filter the most basic knowledge into the slide This step, teachers do well, the electronic lecture plan will ensure knowledge transfer

Step 3 Collection of material related to the content, construction of

documentation

In addition to the collection of materials to supplement and expand knowledge from books and related reference materials; it is important and necessary to build a documentation store This is a necessary condition for effective exploitation of the PowerPoint software program, the more abundant the archives, the higher the possibility of exploitation, the more diverse

Sources for teachers to collect documentation:

- Information on the Internet: This is really a huge information store, we can

search information by topic By search engines, we go to the website related to the topic to find

- The information on the ROM, VCD: Now the information on the

CD-ROM and VCD is very rich, can select the necessary information for the content of the lecture to enter the archives

In addition, the pictures and information related to the content of the lecture are very rich can be an important source for us to add to the archives

Step 4 Develop scripts for electronic lecture plans:

This is an important step in the design of the lecture The construction script must ensure the principles of pedagogy and contents of basic knowledge of the lecture, meeting the set objectives and requirements

Discovering and exploiting the strengths of PowerPoint to enhance the activeness of cognitive processes in learners’ learning activities

Construction scenarios depend on the products that are available in the archives Teachers need to make the right choice to build quality scripts

Step 5 Select the language or demonstration software to build the electronic

lecture

Once the materials are available, the basic knowledge is selected the teacher needs to select the language and the demonstration software to conduct the electronic lectures Depending on the specific content that information on each slide can be text, graphics, pictures, sound and video The text should be brief, dynamic

Use a common, simple font; the color of the text is uniform Presentations should use block diagrams so that participants can immediately see the logical structure of the content to be presented

For each lecture should use the frame, the background color uniform for the slide Limit the use of too bright or contrasting colors On the other hand, it should not be too much to use the demonstration software in a "flying" manner to attract unnecessary curiosity for learners, dispersing the students' attention It is important

to use the demonstration software to focus on the core content, to fully exploit the underlying ideas within the demonstration audience by addressing issues, guidelines, and organization Develop cognitive to develop the thinking of the learner

Finally, make the link between the slides logically This is an important work that creates the advantages of electronic lecture so we need to maximize the linking ability, thanks to this linking ability that the lecture is organized flexibly to help students acquire the knowledge

Step 6 Run the program, repair and finish

After the design is completed, they must be run and check, especially the link

to carry out repairing and finishing

1.3.4 Some notes for designing electronic lectures:

The color of the background: Teachers should follow the principle of contrasts the slideshow will be more prominent For example, when we use dark backgrounds, we use only bright or white text In contrast, we use only bold text (black, dark blue, dark red, etc.) on a white or bright background

Fonts: Fonts should be bold, clear and neat We are using basic fonts such as Times New Roman and Arial of Unicode or VNI-times of VIN-Windows

Size: Select the appropriate font size, the font size of the title is usually 32, the normal letter is 28

Layout content: Teachers should not overlay the background image from top left down to left, which should leave space evenly on both sides and in the

appropriate proportion (usually 1/5), to ensure aesthetics, sharpness and no loss of detail when projected onto the screen

In addition, the pictures, photos or clips may be good, but they are faint we should not be used because it does not provide the information specified as desired

CHAPTER II: ENGLISH LESSON PLANS FOR TEACHING CHAPTER

ELECTROMAGNETIC INDUCTION, PHYSIC 11 TH GRADE

2.1 Structural and content analysis of the “Electromagnetic induction”: 2.1.1 Features chapter:

The "Electromagnetic Induction" chapter is the fifth chapter in the Basic Physics Class 11 program This chapter includes 7 periods: 4 theoretical periods, 2 exercises periods and 1 test

Electromagnetic induction is one of the most fundamental phenomena of electrodynamics This phenomena study is not merely a study of phenomena, but also the accumulation of knowledge that assures the deep understanding and understanding of the physical applications of phenomena to life and technology It can be said that students can only grasp the principle of producing alternating current, the principle of AC and DC generators, when students understand the nature of the phenomenon of electromagnetic induction and the rules governing this phenomenon Moreover, the study of phenomena is based on the knowledge of the phenomenon of electromagnetic induction has been studied before, so once again help students can understand the knowledge Based on this electromagnetic induction, one can explain the presence of electromotive force in a moving wire segment that cuts off magnetic induction lines, explains the inductance phenomenon

as well as the output, Foucault current,

The learning process of the knowledge in this chapter requires and allows students to become acquainted with the specific cognitive methods of physics, in particular the empirical method

Together with the effect to help students master the phenomena, concepts, laws and physical principles of the application, the chapter "Electromagnetic induction" is also a means to practice skills, brain and limbs, thereby broadening the basic understanding while promoting the creative capacity of students

2.1.2 Task of the chapter:

Learn about the phenomenon electromagnetic induction, concepts, laws, and applications related to this phenomenon

2.1.3 Schema logic content knowledge of the chapter:

Figure 1 Schema logic content knowledge of the chapter “Electromagnetic

- Speech Faraday’s law of electromagnetic induction, Lenz’s

law of induced current and write the formula:

Table 1 Standard of knowledge, skills of the chapter “Electromagnetic induction”

2.2 Design the process of teaching electronic lecture in the chapter

“Electromagnetic induction”:

2.2.1 Objectives:

By studying this chapter you should get to understand the nature of the two kinds of electromagnetic induction, the differences between them and their common features To demonstrate this understanding you should be able to explain the principles of electromagnetic induction and discuss examples of each of the two types

2.2.2 Lesson structure:

- Electronic lectureis entirely in English: content, images, videos are in English

- Vocabulary, handouts with relevant questions and problems provided by the teacher at the previous lesson

- Teacher delivers content in English

- The exercises are compiled in English

- State the phenomenon of self-induction

- State self-induction and the unit of self-induction

- State the magnetic field energy of a self-induced solenoid and every magnetic fields carry energy

Skills:

- Do experiment on electromagnetic induction

- Calculate the electromagnetic induction in the case of magnetic flux through a closed circuit that changes over time

- Determine the direction of the induced current according to Lenz's law

- Calculate the self-induced electromotive force in the solenoid when the current passing through it has the intensity varying over time

2.2.3 Specific teaching process:

2.2.3.1 Magnetic flux Electromagnetic induction

UNIT 23: MAGNETIC FLUX ELECTROMAGNETIC INDUCTION

(Period 1)

A OBJECTIVES:

1 Knowlegde: Students will be able to:

- Write the formula and understand the physical meaning of the magnetic flux

- Understand the concept the phenomenon of electromagnetic induction

2 Skills:

- Solve exercises related to flux and electromagnetic induction

- Translate some main vocabulary into Vietnamese:

+ Induce/ produce

+ Electric current/ Electricity

+ Magnet/ Magnetic field/ Magnetic field lines/ Magnetic flux

+ Initial magnetic field/ final magnetic field

+ Electromagnetic induction

+ Experiment

+ A closed circuit/ Battery/ Galvanometer

+ Wire/ a loop/ a coil/ a soleniod

+ Direction

+ Intensity

+ Induced current/ induced voltage

+ Right hand rule

3 Attitude:

- Positively related knowledge to reality

- Enjoy and be active in learning professional vocabulary

1 Vocabulary:

- Induce/ produce

- Electric current/ Electricity

- Magnet/ Magnetic field/ Magnetic field lines/ Magnetic flux

- Initial magnetic field/ final magnetic field

- Electromagnetic induction

- Experiment

- A closed circuit/ Battery/ Galvanometer

- Wire/ a loop/ a coil/ a solenoid

- Direction

- Intensity

- Induced current/ Induced voltage

- Right hand rule

2 Main contents:

a The formula of magnetic flux:

The names and units of the quantities in the formula:

The unit of magnetic flux:

b The phenomenon of electromagnetic induction:

3 The state of Lenz’s law:

4 The Foucault current:

- Homework

- Table content:

PERIOD 44 - UNIT 23: MAGNETIC FLUX

2 The unit of magnetic flux:

In the SI system, the unit of magnetic flux is weber

Symbol: Wb

In the formula if S = 1m2 and B = 1T, Φ = 1Wb

II The phenomenon of electromagnetic induction:

C ACTIVITIES IN CLASS:

1 Activity 1: Information Faraday

Michael Faraday (born Sept 22, 1791 - die in 1867) was a British physicist and chemist who is best known for his discoveries of electromagnetic induction and of the laws of electrolysis His biggest breakthrough in electricity was his invention of the electric motor In Faraday's first experimental demonstration (August 29, 1831),

he wrapped two wires around opposite sides of an iron ring or "torus" (an arrangement similar to a modern toroidal transformer) Based on his understanding

of electromagnets, he expected that, when current started to flow in one wire, a sort

of wave would travel through the ring and cause some electrical effect on the opposite side He plugged one wire into a galvanometer, and watched it as he connected the other wire to a battery He saw a transient current, which he called a

"wave of electricity", when he connected the wire to the battery and another when

he disconnected it This induction was due to the change in magnetic flux that occurred when the battery was connected and disconnected

2 Activity 2: Magnetic flux

Teacher's activities Students' activities

- Observe the simulated fish catcher

+ Surface area of the fish basket: A

+The angle between the 𝐯⃗ and the line is

perpendicular to surface area of the fish

 the amount of fishes going into the

basket = N.A.cosα

- How to express the number of

magnetic field lines through a certain

area?

- Consider a plane of area A in a uniform

magnetic field 𝑩⃗⃗ that makes an angle 𝜶

with the normal 𝒏⃗⃗ of the plane The

magnetic flux Φ through the plane A:

- Show the video

- In the video, ϕ depends on B, A, α

- Consider the different cases of :

The magnetic flux depends on the

angle between the 𝐵⃗ , 𝑛⃗

- Listen and copy

- Think and answer

- Observe

- Listen carefully

-  = 00 , cos  =1  max = BA

If A = 1m2 , B = 1T ,  = 1 Tm2

- In the SI system, the unit of magnetic

flux is Tm2 , defined as a weber (Wb)

1Wb = 1T.1m2 = 1T.m2

- Listen and copy

- If choose S=1m2, α = 0o then Φ=B - Magnetic flux equals the magnetic field

What does the magnetic flux mean? lines through a unit area

- For the purpose of introducing the

concept of magnetic flux, we go to the

next section "The phenomenon of

electromagnetic induction”

3 Activity 3: The phenomenon of electromagnetic induction

Teacher's activities Students' activities

- Show the video of the phenomenon of

- Explain: Let the magnet move near or

away from the (C), the magnetic field

lines passing through the wire coil

- Observe and answer

- Listen

- Show the video

- What’s happen when we replace the

magnet by an electromagnet?

+ When we change the current passing

through the electromagnet, the induced

current I still appear in the closed circuit

- Conclusion:

- Observe

- Discuss and answer

+ Each time the magnetic flux passing

through the closed circuit (C) varies,

- Listen and copy

there is a current called induced current

in the closed circuit (C)

+ The appearance of induced current in

(C) is called the phenomenon of

electromagnetic induction

+ The phenomenon of electromagnetic

induction only exits in the time that the

magnetic flux passing through the closed

circuit varies

4 Activity 4: Apply and consolidate

Teacher's activities Students' activities

- Summary:

+ Definition, calculation, the unit and

meaning of the magnetic flux

+ The phenomenon of electromagnetic

induction

- Listen

- Complete the Study slip of the period 2

of “Magnetic flux Electromagnetic

induction” and homework

CROSS WORD OF MAGNETIC FLUX

ELECTROMAGNETIC INDUCTION

Across

1 What is the phenomenon of induced current? (two words)

3 What does the number of magnetic field lines through a certain area? (two words)

5 The unit of magnetic flux

Down

2 Many loops of wire placed one on top of another

3 A bar or mass of steel or iron that has the property of attracting certain substances like iron

4 What does the word with the same meaning as change?

Figure 3 KEY

Figure 4 HOMEWORK

PERIOD 44 - UNIT 23: MAGNETIC FLUX

c The phenomenon of electromagnetic induction:

Translate and complete the following exercises:

Problem 2: A circular loop of wire us exposed to an external magnetic field of

magnitude 2T Radius of the circle 1,5cm The magnetic field lines and the normal of the loop plane make an angle of 300 What is the magnetic flux of the

loop?

Problem 3: A rectangular loop of wire with dimensions 0.2 m x 0.5 m is placed

in a uniform magnetic field of magnitude 2 T The magnetic field is perpendicular to the plane of the loop What is the magnetic flux in the loop?

UNIT 23: MAGNETIC FLUX ELECTROMAGNETIC INDUCTION

(Period 2)

A OBJECTIVES:

1 Knowledge: Students will be able to:

- Speech of Lenz’s law of induced current

- Speech and tell some applications of the Foucault current

2 Skills:

- Applied the Lenz’s law to determine the direction of induced current in different

cases

- Translate main vocabulary into Vietnamese

+ Induce/ create/ produce

+ Electric current/ Electricity

+ Magnet/ Magnetic field/ Magnetic field lines/ Magnetic flux

+ Initial magnetic field/ final magnetic field

+ Electromagnetic induction

+ Experiment

+ A closed circuit/ Battery/ Galvanometer

+ Wire/ a loop/ a coil/ a soleniod

+ Direction

+ Induced current/ induced voltage

+ Right hand rule

3 Attitude:

- Seriously interested in learning

- Positively relates knowledge to reality

- Enjoy and be active in profession vocabulary

I Lenz’s law on the direction of inductive current:

The content of the Lenz’s law:

The induced current in a loop is in the direction that creates a magnetic field that opposes the change in magnetic flux through the area enclosed by the loop

II Foucault current:

1 Experiment 1:

2 Experiment 2:

3 Explain:

4 Applications of Foucault current:

- Applied in electromagnetic brakes of heavy automobiles

- Causes thermal radiation effect to apply in inductive furnaces to heat metals

- Application in many fields: electricity meter, electromagnetic machine, transformer

Figure 6

Problems: Before we know when the magnetic flux varies through the closed

circuit, in the circuit appears induced electromotive force, expressed in the circuit with electric current deflected needle galnavometer However, we have not determined the direction of the induced current and the magnitude of the induced electromotive force In this section, we will look at the direction of induced current flowing in the circuit and find out the formula for determining the magnitude of the induced electromotive force in the closed circuit

2 Activity 2: Lenz’s law on the direction of induced current

Teacher's activities Students' activities

- Give picture:

+ Φ increase

- Observe

+ Φ decrease

- Conclusion: The induced current in a

loop is in the direction that creates a

magnetic field that opposes the change

in magnetic flux through the area

enclosed by the loop  The state of

Lenz’s law

- Listen and copy

3 Activity 3: Foucault current

Teacher's activities Students' activities

- Show the video - Observe

- What is the Foucault current?

- Feedback: The induced current

created in the mass of the conductor

when the conductor moves in the

magnetic field or are put in a time

varying magnetic field is called the

Foucault current

- Tell some applications of Foucault

- Discuss and answer

- Listen and copy

- Answer

current

- Give information:

+ Electricity meter: Attach one end of

the needle to a small metal plate

(copper or aluminum), placed in the

magnetic field of a permanent magnet

When the needle move  the metal

disk is moved  ϕ is varies  appear

the Foucault current in the disk  the

needle swings are turned off quickly

+ Electromagnetic stove: This cooker is

made, within a few millimeters of the

kitchen surface, a variable magnetic

field The bottom of the metal pot in the

magnetic field will heat up, cook the

food

+ Electric fan: In transformers and

electric motors, their iron cores lie in

the variable magnetic field In the core

there are Foucault currents Due to the

Joule-Lenz effect, the energy of the

Foucault streams is converted to heat,

which in turn accelerates heat,

consumes a portion of energy and

reduces the efficiency of the machine

- Listen

- The Foucault current causes useless

energy losses How to reduce the harm

of the Foucault current?

- Feedback: Reduce the Foucault

currents by increasing the resistance of

the cores Use thin iron sheets that are

- Discuss and answer

insulated and bonded together so that

the slices are parallel to the direction of

the magnetic field

4 Activity 4: Apply and summary

Teacher's activities Students' activities

- Summary: - Listen and remember

- Give exercises - Complete

Quiz 1: The unit of magnetic flux is:

A Henry

B Weber

C Ampereturn / weber

D Ampere / meture

Quiz 2: Total number of magnetic

field lines passing through an area is

B The phenomenon of electromagnetic

induction/ inductive current

C Inductive current / magnetic flux

D Magnetic flux / inductive current

Quiz 4: The law that the induced EMF

and current always oppose the cause

producing them is due to:

ELECTROMAGNETIC INDUCTION

(Period 2) Problem 1: The state of Lenz’s law

Apply: Determine the induction current direction in the following cases:

1 A bar magnet is moved towards a vertical conducting ring that is suspended at the end of a string What happens to the ring during the time

when the magnet approaches it?

A The ring will move toward the magnet

B The ring will move away from the magnet

C The ring will remain stationary

D The ring will tend to turn in clockwise direction

E The ring will tend to turn in counter-clockwise direction

2 A bar magnet with the north pole faced downward is

held above a horizontal circular coil Which of the

following statements about the induced current is true

(viewed from above)?

A The induced current flows in a clockwise direction

B The induced current flows in a counter-clockwise

E There is no induced current in the coil

3 A bar magnet with the north poles faced downward

is dropped above a horizontal circular coil Which of

the following statements about the induced current is

true (viewed from above)?

A The induced current flows in a clockwise direction

B The induced current flows in a counter-clockwise direction

C The induced current flows first in a clockwise and then in a clockwise direction

counter-D The induced current flows first in a counter-clockwise and then in a clockwise direction

E There is no induced current in the coil

Problem 2: Foucault current:

a Definition:

b Applications of Foucault current:

c How to reduce the harm of the Foucault current?

2.2.3.2 The induced electromotive force

UNIT 24: THE INDUCED ELECTROMOTIVE FORCE

A OBJECTIVES:

1 Knowledge: Students will be able to:

- The statement defines the induced electromagnetic force of the closed circuit

- Understand and speech Faraday's law Write expressions to calculate the induced electromotive force

- Describe the relationship between the induced electromotive force and Lenz’s law

- Understand the nature of electromagnetic induction is the transformation from mechanical energy to electric energy

2 Skills:

- Apply the learned formula to calculate the electromagnetic induction in some simple cases

- Translate main vocabulary into Vietnamese

+ Electromotive force/ Induced electromotive force

- Seriously interested in learning

- Positively relates knowledge to reality

- Enjoy and be active in profession vocabulary

B PREPARE:

1 Teacher:

- Powerpoint

- Videos on the induced electromotive force

- Study card

STUDY CARD UNIT 24: INDUCTIVE ELECTROMOTIVE FORCE

The induced electromotive force:

The formula of Faraday’s law:

The names and units of the quantities in the formula:

- Homework

- Table content

PERIOD 46 - UNIT 24: INDUCED ELECTROMOTIVE FORCE

I The inductive electromotive force in the closed circuit:

ξc: inductive electromotive force (V)

∆ϕ: The magnetic flux flows through the circuit varies in a time ∆t

If we only consider the magnitude of ξc , then:

The magnitude of the induced electromotive force in a closed circuit is proportional to the speed of magnetic flux variation through that closed circuit

II The relation between the induced electromotive force and Lenz’s law:

The induced electromotive force is opposite to the variation of magnetic flux

III The energy transformation in the phenomenon of electromagnetic induction:

The nature of the mentioned phenomenon of magnetic field induction is a transformation process of mechanical energy into electric energy

Teacher's activities Students' activities

Question 1: What is the magnetic flux?

Formulas of magnetic flux

- Answer questions

Question 2: What is electromagnetic

induction?

Question 3 : Determine the direction

induced current in the following cases:

a B decrease b B increase

Problems: When induced current occurs in the circuit, the induced

electromagnetic force will appear What are the characteristics of electromagnetic

.

induction? Today's lesson will help us answer that question Unit 24: "INDUCED ELECTROMOTIVE FORCE"

2 Activity 2: The induced electromotive force in a closed circuit

Teacher's activities Students' activities

- When a current is present in the

circuit, it shows that there is an

electromotive force producing that

- Answer

- When there is variation magnetic flux

passing through the closed circuit, an

induced current will appear in the

circuit What does the inductive current

in the circuit show?

- Feedback: In a circuit there exits

electromotive force that produces the

current

- Discuss and answer

- The appearance of the induced

current in a closed circuit (C) shows the

existence of a power supply in that

circuit The electromotive force of the

power supply is called induced

- Listen and remember