Download Electricity, Magnetism, and Waves

Physics 11b
Electricity, Magnetism, and Waves
Harvard University
Spring Term 2010
2/21/10 (See Revision Notes at the end)
Course Information for
Physics 11b
Electricity, Magnetism, and Waves
Course Overview
This is the second term of the Physics 11 series. The first term, Physics 11a, dealt
with classical mechanics. Mechanics tells us how a system reacts when acted on by a
force. There are only two forces that act on a macroscopic scale and, in so doing, directly
affect our everyday lives. One is gravity, which was discussed in Physics 11a. The other
is electromagnetism, the main subject of this course.
You may ask, “What about all the other forces we learned about in Physics 11a?”
What about the normal force that prevents us from falling through the floor, or the
frictional force that allows us to walk, or the chemical force that allows gasoline to propel
our cars. The answer is that they are all electromagnetic forces. Indeed, with the
exception of gravity, every force we encounter in our everyday lives is an
electromagnetic force.
The theory of electromagnetism was developed in the 18th and 19th centuries in bits
and pieces by many people, some of whose names you will encounter, such as Coulomb,
Faraday, and Ampère. But it was all put together by James Clerk Maxwell in 1873 in his
magnificent A Treatise on Electricity & Magnetism. This formulation, completely valid
to the present day, did for electromagnetism what Newton’s Principia did for gravity.
From Maxwell’s work it became clear that light is caused by electromagnetic forces
and that it could take many forms, many of which had yet not been seen, such as radio
waves and x-rays. Accordingly, we will also study some of the properties of light, in all
its forms, and how it can be used.
There is one other subject that we will spend a little time on at the very end of the
course, thermodynamics. This is a subject that is more related to the material of Physics
11a than that of 11b, but it was not covered there. However, it is a subject about which
every person, let alone every scientist, should have some understanding.
Prerequisites
Students should have an understanding of classical mechanics at the level of Physics
11a. The course will use elementary calculus, with some use of line, surface, and volume
integrals. Mathematics at the level of Math 19a, Math 21a, or Applied Math 21a will be
useful, but probably not essential.
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Electricity, Magnetism, and Waves
Active Learning and Just-in-Time Teaching
Over the years, many of us have become increasing dissatisfied with the way almost
all science courses have been taught up to now: Reading is assigned prior to each lecture,
which most students do not read. The instructor, knowing this, feels that the function of
the lecture is to convey information, most of which was already in the reading. The pace
of the lecture is too fast for the student to follow it completely in real time, so the student
leaves the lecture with, at best, a vague understanding of the information that the
instructor had tried to convey. This is clearly not the best use of the valuable classroom
time.
This is not the model that your courses in the humanities follow. If you were taking a
course in Shakespeare, for example, you would not think of attending a lecture on Hamlet
without first having read the play, and you would certainly not expect the instructor to
read the play to you.
A different model has been demonstrated to be a much more effective teaching
technique. This is known as “just-in-time teaching.” Here is the way it works: You will
be assigned reading prior to each class meeting. By midnight of the day prior to the class
meeting, you will complete a brief online questionnaire. It will contain three questions.
The first two will verify that you have finished the reading and will “test” your
understanding of it. The last, and most important, question will ask you what you found
most difficult in the reading. (In case of a server failure, just email me your answer to the
third question.)
During the class meeting (or what we might call the “interactive lecture”) we will
review those areas with which you have indicated that you have had the most difficulty.
We will also conduct demonstrations and give you some multiple-choice questions
designed to help you with conceptual understanding of the material. Some of the time we
may ask you to discuss your answer with students sitting near you and then answer the
question again.
On both the pre-class meeting questionnaire and the class meeting questions, you will
not be graded on correctness, but on effort. (See evaluation below.)
Our experience with just-in-time teaching is that it changes the dynamic of the class
meeting. Students come to class knowing that they need a better understanding of some
of the material and are ready to ask questions. Students who have a good grasp of the
material gain a deeper understanding than they would have otherwise.
Although this technique will put some constraints on your time, I believe that it will
allow you to master the material more effectively, and in the end, reduce the total amount
of time that you will need to spend on the course.
Readings
We will try to assign reading five days before each class meeting. The text will be
the same as in Physics 11a, Douglas Giancoli’s Physics for Scientists and Engineers. The
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Electricity, Magnetism, and Waves
material on electromagnetism is in volume 2; the material on thermodynamics is at the
end of volume 1.
Course Web Pages
The course web pages (http://courses.physics.harvard.edu/11b) will be an important
means of communication in the course. You will logon to the web site to complete your
questionnaires. All assignments and handouts will be posted there. The page should be
reachable through your Harvard portal.
Your first “assignment” is to enroll in the course by registering on the web site. Click
on “Sign in” and then on the “Not enrolled” link. Complete the form
Class Meetings
Class meetings will be in Science Center B, 9:30-11:00 TT. We will start promptly at
9:40 am.
PRS System
During class meetings we will use a PRS (Personal Response System) from Turning
Technologies. Most of you are familiar with this from Physics 11a. You have two
options, either a Turning Point Response Card which is a credit card size device, or a
Turning Point ResponseWare License for a web-enabled mobile device or a laptop.
You can purchase a Turning Point Response Card (RFC-02) from the Coop for
$41.65 or directly from Turning Technologies for $28. If you buy the card from the
Coop, I understand that they will buy it back from you at the end of term for about half
price. You may also be able to buy a used card from the Coop. The cards are for sale at
the same place as the textbooks. If you want to buy it from Turning Technologies, go to
https://store.turningtechnologies.com/ and enter the Harvard code 4yQj. (If you do not
enter the code, you do not get the Harvard discount.)
If you need a license for a web-enabled phone or a laptop, go to the web site given
above and enter the Harvard code. The licenses range from $15 for 6 months to $32 for 5
years. ResponseWare apps for iPhones and Blackberries are available at
http://www.turningtechnologies.com/responsesystemsupport/downloads/ .
Once you have your response card or your license, you need to register your ID at
http://student.turningtechnologies.com/ . The device ID on the response card is on the
reverse side. Enter your student ID in the Other Info box. Enter
[email protected] in the box for the instructor email and hit Display Classes.
Physics 11b will appear. Select it and hit Add and the course will appear in the right box.
Then hit Next, review the information, and complete the registration.
Bring your device or clicker to every class meeting. We will start using them on
January 28. If you are using a laptop or a mobile device, point your browser to
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Electricity, Magnetism, and Waves
http://www.rwpoll.com/ or use your app. Using someone else’s clicker or otherwise
impersonating another student in class constitutes academic dishonesty.
Sections and Instructional Staff
A weekly one-hour to one-and-a- half section will be arranged and will deal largely
with problem solving, clarifying material from and discussing issues raised in the reading
and class meetings. Sections are not mandatory, but most of you will find them useful.
The first meeting of sections will be the week of February 1. For that week, attend
any section you want. For the following weeks, you will be assigned a section.
Registration for sections and labs will be done using the Registrar’s sectioning software.
Await instructions.
The section schedule and staff and other instructional staff is given below:
Section
Day/Time/
Room
Monday
1:30-3:00
Lyman 330
Hyoseok Yi
Leaders
Email/Phone/
Office/Office Hours
[email protected]
455-2997
Maxwell-Dworkin 321
Wed 8-10 pm in Leverett House
Monday
3:00-4:30
Jefferson 256
Hyoseok Yi
[email protected]
455-2997
Maxwell-Dworkin 321
Wed 8-10 pm in Leverett House
Monday
7:00-8:30
Jefferson 256
Alexa Hart
[email protected]
495-7182
160 Concord Ave. 234
Mon 4-5
Tuesday
1:30-3:00
Lyman 330
Chris Chou
(Head TF)
Tuesday
3:30-5:00
Lyman 330
Chris Chou
(Head TF)
[email protected]
TBA
Jefferson 251
Tue 5-6
Wed 3-4
[email protected]
TBA
Jefferson 251
Tue 5-6 and Wed 3-4
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Electricity, Magnetism, and Waves
Tuesday
7:00-8:30
Jefferson 256
Jihye Seo
[email protected]
230-3758
Jefferson 472
Tues 6-7 and Wed 6-7
Wednesday
2:30-4:00
Science Ctr.112
Masha Baryakhtar
[email protected]
549-7553
Jefferson 251
Thu 11-12
Wednesday
4:00-5:30
Lyman 330
Robbie Martinez
[email protected]
495-3212
Lyman 430
Wed 3-4
Wednesday
7:00-8:30
Jefferson 356
Jihye Seo
[email protected]
230-3758
Jefferson 472
Tues 6-7 and Wed 6-7
Other Instructional Staff
Gary Feldman
(Professor)
[email protected]
496-1044
Lyman 232
Thu 12:30-2:30
Markus Greiner
(Professor)
[email protected]
495-9875
Jefferson 353
TBA
Waseem Bakr
(Lab TF)
[email protected]
495-0843
Lyman 137
TBA
Jieping Fang
(Lab TF)
[email protected]
495-9076
Lyman 121
TBA
Jon Poage
(Lab TF)
Photo not
available.
[email protected]
TBA
TBA
TBA
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Electricity, Magnetism, and Waves
In addition, Robert Hart ([email protected]), the physics lab coordinator, will
be an important resource of help and advice. He is very knowledgeable about the
hardware and software that we use in the labs.
In addition to the office hours posted above, we are all also available by appointment.
Laboratories
Physics is an empirical science. We make observations and develop theories; theories
make predictions and become sounder if these predictions can be demonstrated
experimentally. Hand-in-hand with the theoretical part of this course are the
experimental labs. These will be set up to demonstrate many of the phenomena discussed
in lecture. Come prepared.
Laboratory Goals
1. The labs are designed to introduce important experimental concepts and analytical
skills that are useful, not only in physics, but in many different circumstances. They
will also provide you with an appreciation of the uncertainty associated with
measurement and an understanding of the distinction between experimental
uncertainties and errors in reading and recording information.
2. The labs are also designed to reinforce some of the fundamental physics concepts
covered in lecture and to help you master these concepts. There will be a strong
correlation between the labs work and what is being covered in lecture.
3. Science is a team endeavor, with even the greatest minds of our century working in
groups to complete experiments that split the atom, discovered the top quark, and
measured the expansion of the Universe. Like professional scientists, you will work
in teams, brainstorming new ideas and learning from one another. These laboratories
should help you develop collaborative skills that are vital to success in many
endeavors
Laboratory Scheduling
You will each do five labs. There will be six lab sections, each of three hours and all
in Science Center 104:
Day
Tues
Wed
Thur
Fri
Time
1-4 pm
2-5 pm
2-5 pm
1-4 pm
Time
7-10 pm
7-10 pm
The labs will start the week of February 15 and then be every other week, except for
spring break. The schedule is
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Week beginning
February 15
March 1
March 22
April 5
April 19
Electricity, Magnetism, and Waves
Laboratory
DC Circuits
Capacitors
Automobile Ignition
Microscope
Interferometer
Pre-Laboratory Assignments
The lab manual and any additional documentation will become available the week
prior to the lab. The time in lab is usually very limited so you should read all the material
thoroughly before the lab. If you don’t do this, you will likely find that you won’t have
time to finish the lab in the allotted time. Please come prepared.
Each lab has pre-lab questions that need to be answered before the labs. The pre-lab
assignments are due at the beginning of the Tuesday lecture on the same week as the lab.
This applies to everyone independent of the session
The Laboratory
There will be a maximum of 21 people in each lab section with seven tables. You
break up into teams of three. Try to find compatible partners; if not we shall triple you
up with others.
We would really like to emphasize the need to do collaborative work. You will be
engaging in the lab with two other colleagues. It is of major importance that everyone
contributes and we strongly encourage discussions with your colleagues, but also with the
TFs and with Professor Greiner. Everyone should take an active part in the
experimentation, collecting the appropriate data, discussing the analysis and recording the
results.
The Laboratory Report
The lab report will be done as the lab progresses and it is due at the end of the lab
session. There will only be one lab report per group. The completed report should be
turned in at the end of the lab. There is no required post-lab work.
Laboratory Assessment
There are five labs this term and together they count 15% towards your final grade.
(See Evaluation below.) The labs are evaluated on a 3-point scale divided equally by the
three main components: pre-lab work (1 point), work done in lab (1 point), and lab report
(1 point). Extra credit can be given for exceptional work
Problem Sets
There will be weekly problem sets, with the exception of weeks in which there is an
inclass exam. The problem sets will be posted after the Thursday class meeting and be
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Electricity, Magnetism, and Waves
due by 5 pm the following Thursday. They should be placed in the locked box near
Science Center 110. Late problem sets will be accepted until 10 am the following
Monday morning, but will only receive half credit.
The problem sets are primarily for instruction rather than evaluation. Thus, you may
collaborate on them and you may seek help form any source. However, you must write
up your own work. On your submission, please indicate the names of people you have
collaborated with.
We encourage collaboration on problem sets and will help you set up voluntary study
groups early in the course. The correct way to use study groups is to attempt the problem
sets on your own, and then get together with your group to discuss your answers. You
will not gain much from the problem sets if you go into your study group cold, and the
other group members may not appreciate your lack of a contribution.
We also remind you that there is a traditional gathering of physics students to work
on problem sets Wednesday nights in the Leverett House dining room.
Exams
The exams will be open book, open notes. The first inclass exam covers electricity. The
second inclass exam will emphasize magnetism and the interactions between electricity and
magnetism through the production of electromagnetic waves. The final exam will be
comprehensive, but give special emphasis to optics and thermodynamics, which were not
covered by an inclass exam.
Evaluation
The components of the course grade will be
Problem sets
Laboratory
Effort on pre-class meeting questionnaires
Participation with the PRS system
Final exam
And the best two out of three of the following:
First in-class exam
Second in-class exam
Final exam
15%
15%
10%
6%
18%
18%
18%
18%
The lowest problem set score will be dropped. You will also be allowed to miss three
pre-class questionnaires and three class meeting PRS participations without penalty.
There are no makeups for missed in-class exams. Thus, it is never to your advantage
to miss an exam.
Also note that exams account for only 54% of the grade. The other 46% is crucially
important because conscientious students will get almost full credit for it, while the exam
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Electricity, Magnetism, and Waves
scores are usually quite a bit lower. Thus, exams may effectively account for less than
50% of the final grade..
Grades for this course are not curved because we want to encourage cooperation and
peer instruction. You should not feel that you are competing against other students, but
rather helping each other to understand the material.
The minimum course score for each grade is
Grade
A
AB+
B
Min Score
90
84
78
73
Grade
BC+
C
C-
Min Score
68
64
60
56
Grade
D+
D
D-
Min Score
52
48
44
These minimum scores are based on the assumption of exams of moderate difficulty. We
reserve the option of lowering them slightly if we feel that the exams proved more
difficult than we expected. However, in no case will we raise them.
Instructors
Professor Feldman will run most of the class meetings and is responsible for writing
the problem sets and exams. Professor Greiner will run the laboratories and may run
some of the class meetings.
The teaching staff, including contact information and office hours, are listed above
under Sections and Instructional Staff.
Secretary
Ms. Angela Allen will be the course secretary. Her office is Jefferson 242 and her
phone is 495-3072.
Class Meeting Schedule
Date
Jan 26
Jan 28
Feb 2
Feb 4
Feb 9
Feb 11
Feb 16
Feb 18
Feb 23
Feb 25
Mar 2
Topic
Introduction
Electric Charge and Field
Gauss’s Law
Electric Potential
Capacitance and Dielectrics
Electric Current and Resistence
DC Currents
Magnetism
Magnetic Sources 1
Magnetic Sources 2
Electromagnetic Induction
Chapter
21
21
22
23
24
25
26
27
28
28
29
PS Due Lab
1
2
3
1
1
4
2
Physics 11b
Mar 4
Mar 9
Mar 11
Mar 16
Mar 18
Mar 23
Mar 25
Mar 30
Apr 1
Apr 6
Apr 8
Apr 13
Apr 15
Apr 20
Apr 22
Apr 27
May 4
May 11 ?
10
Electricity, Magnetism, and Waves
Inclass Exam 1 (covers chapters 21-26)
AC Currents 1
AC Currents 2
Spring Break
Spring Break
Maxwell’s Equations
Electromagnetic Waves
Light Reflection and Refraction
Lenses and Optical Instruments
Interference
Inclass Exam 2 (covers chapters 21-31)
Diffraction and Polarization
Temperature and the Ideal Gas Law
1st Law of Thermodynamics
2nd Law of Thermodynamics 1
2nd Law of Thermodynamics 2
2
30
30
31
31
32
33
34
35
17-18
19
20
20
5
6
3
3
7
4
4
8
9
5
5
10
Final Exam
Note that the final exam date is tentative. The Registrar schedules it and he retains
the right to change it up to the time that it is announced. Thus, you should not make
travel plans until final exam dates are posted.
Revision Notes:
1/25/10a: Added TF phones, offices, and office hours.
1/26/10: Added phone and office for Alexa Hart.
1/26/10a: Clarified that the footnote on the Wed 12:30 section referred only to Feb 3.
1/28/10: Posted late problem set policy.
Moved Wed 12:30-2 section to 2:30-4.
Moved Masha Baryakhtar’s office hours to Thur 11-12.
Corrected Chris Chou’s email.
1/31/10 Wed 2:30-4 section meets in Science Center 112.
1/31/10a Corrected Alexa Hart’s email.
2/2/10
Changed Gary Feldman’s office hours to Thursdays, 12:30-2:30.
Added a location for Masha Baryakhtar;s office hours.
2/2/10a Added a location for Chris Chou’s office hours.
2/9/10
New section and staff list.
Corrected Jon Poage’s email.
2/10/10 Corrected the second Wednesday section time.
2/12/10 Changed Hyoseok Yi’s office hours to 8-10 pm in Leverett House.
2/21/10 Removed 3/18 problem set due date.