8.07 - Electromagnetism II Fall 2014

Lecturer:  Prof. Alan Guth
Recitation Instructor:  Prof. Xiao-Gang Wen
Teaching Assistant:  Anton Goloborodko

Announcements:

Announcements will be posted here throughout the semester.

FRI 10/24/2014: Quiz 1 histogram, with estimated letter grades, is posted
Dear 8.07 Students,
I have just posted a histogram of the grades for Quiz 1, with estimated letter grade equivalents. It is on the Exams tab of the class website. As it says on the histogram page,

  The grade cuts shown represent my estimate of what you have earned on this quiz, but they will not necessarily be the numerical cuts that will be used to evaluate your final grade. The final grade cuts will be adjusted to account for the level of difficulty of all the quizzes and problem sets.

We have tried to grade as carefully as we can, but grading errors are still possible. If you have any questions about the grading of your quiz, I encourage you to ask about it. I graded problems 2 and 3, and Anton graded problem 1, so it might be most efficient for you to start by discussing it with the person who graded the problem in question. But you can discuss the grading with any of the course staff. Both Anton Goloborodko and Prof. Wen are authorized to change grades, as well as me, but any of us might refer the question to the original grader, especially in evaluating partial credit. In any case, if you are unsatisfied with the decision of Anton or Prof. Wen, you should always feel free to come to me, and I will be happy to consider your point of view. In the end, I hope to make sure that the grading in this course is fair, and that hopefully you will all agree that it is fair.
The same issues apply to problem set grades. If you have any questions about the grading of your paper(s), going back to the beginning of the term, I encourage you to ask about it. For the homework it would probably be most efficient for you to first talk to Anton, but I am very much available to consider any points of disagreement.
Best wishes,
— Alan Guth —

FRI 10/24/2014: Fringing fields: correction to Wed 10/22 lecture
Dear 8.07 Students,
There was an item that I intended to mention in lecture today, but forgot. This past Wed (10/22/14), I drew on the blackboard a diagram of a capacitor that was initially filled with a dielectric slab, but the dielectric was pulled part way out. Where the dielectic is sticking out of the capacitor plates, the nearly uniform E-field inside the capacitor changes smoothly into the very small field outside of the capacitor, and that leads to a fringing field pattern. I showed that (qualitatively) correctly in my diagram. At the other end of the dielectric, however, where the edge of the dielectric slab is well within the capacitor, the diagram I drew in lecture was not accurate. I showed fringing fields here, too, but that is not correct. Since the potential difference between the two capacitor plates is constant throughout the capacitor, the electric field need not have any discontinuity at the edge of the dielectric. As long as the edges of the capacitor are far away, there is a solution in which the E-field is completely uniform between the capacitor plates, pointing perpendicular to the plates (just as inside a vacuum-filled capacitor). This satisfies div D = 0 and curl E = 0 inside each region, as it must. At the edge of the dielectric it satisfies the right boundary conditions: E-parallel is continuous across the boundary, since E is uniform; and D_perp is continuous, since it is zero on both sides of the boundary. Thus this configuration satisfies all the requirements, and therefore is the unique solution to the problem.
A good diagram of this situation can be found at
http://teacher.pas.rochester.edu/PHY217/LectureNotes/Chapter4/LectureNotesChapter4.html#Heading712
in Figures 4.13 and 4.14.
Sorry for the previous confusion, and I hope that this email straightens things out.
— Alan Guth —

WED 10/08/2014: Problem Set 4 Solutions are posted
Dear 8.07 Students,
The solutions to Problem Set 4 are now posted, on the Problem Sets tab of the course web page.
— Alan Guth —

TUES 10/07/2014: Rooms for Review Session and Quiz
Dear 8.07 Students,
The Review Session for Quiz 1 will take place at 7:30 pm on Wednesday evening, October 8, in Room 26-310. It will be run by Anton Goloborodko.
Quiz 1 will take place at 7:30 pm on Thursday evening, October 9, in the TEAL Room, 26-152. You will have two hours to do the quiz, although it will be intended as a one-hour quiz.
Best wishes for the quiz,
— Alan Guth —

SAT 10/04/2014: Problem Set 3 Solutions are posted
Dear 8.07 Students,
The solutions to Problem Set 3 are now posted, on the Problem Sets tab of the course web page.
— Alan Guth —

THURS 10/02/2014: Lecture Notes 4 are posted
Dear 8.07 Students,
I just posted a set of lecture notes, Lecture Notes 4, on the "Traceless Symmetric Tensor Approach to Legendre Polynomials and Spherical Harmonics". They are based on Lecture Notes 9 of 2012, but I made a few improvements in the editing. In particular, the equation that is now Eq. (4.32) has been corrected.
— Alan Guth —

SAT 09/20/2014: Lecture Notes 3 posted (addendum to Wed's lecture)
Dear 8.07 Students,
When I ran out of time in lecture last Wednesday (9/17/14), there were two topics that I did not have time to discuss. Since these topics are relevant to Problem Set 2, and are not discussed in Griffiths' textbook, I wrote Lecture Notes 3 to fill in the gaps. You can access them on the Lecture Notes tab on the course website.
You will probably find these notes useful in completing Problem Set 2.
Best wishes,
— Alan Guth —

MON 09/15/2014: Problem Set 1 Solutions are posted
Dear 8.07 Students,
The solutions to Problem Set 1 are now posted, on the Problem Sets tab of the course web page,
    http://web.mit.edu/8.07/www
— Alan Guth —

SAT 09/13/2014: Problem Set 2 is posted
Dear 8.07 Students,
Hi from San Francisco.
Problem Set 2 is posted, so you can start whenever you find the time. Since Friday Sept 19 is a student holiday, the due date for the problem set is postponed until the following Monday, Sept 22.
Best wishes,
— Alan Guth —

WED 09/10/2014: Lecture Notes 1 and 2 are posted
Dear 8.07 Students,
Hi from Oslo.
I just wanted to let you know that Lecture Notes 1 and 2 have been posted, on the Lecture Notes tab of the course website. These are notes on "Vector Analysis," and "Rotations in Index Notation," which you may find useful in doing this week's homework.
Best wishes,
— Alan Guth —

THU 09/04/2014: Course Information Sheet is posted
Dear 8.07 Students,
An information sheet describing 8.07 is now posted, on the General Info tab. Let me know if you have any questions that are not answered in this handout.
— Alan Guth —

WED 09/03/2014: Problem Set 1 is posted
Dear 8.07 Students,
I just thought that I would let you know that Problem Set 1 is now posted on the course website. The home page is at
    http://web.mit.edu/8.07/www
from which you can click on "Problem Sets".
As I mentioned in lecture, it will be due on Friday, September 12, at 5:00 pm. You should turn in the problem sets at the Physics Department homework boxes, which are at the intersection of buildings 8 and 16, on the third floor of bldg. 8 and the 4th floor of bldg. 16.
— Alan Guth —

TUES 09/02/2014: Welcome to 8.07!!!
Welcome to 8.07, for fall 2014. This web page is not set up yet, but the course this fall will strongly resemble the course I taught two years ago, which is archived on OCW at
http://ocw.mit.edu/courses/physics/8-07-electromagnetism-ii-fall-2012/

Prof. Xiao-Gang Wen will be teaching the recitations this fall, and Anton Goloborodko will be the teaching assistant. The lectures will take place from 11:05 am to 11:55 am on Mondays, Wednesdays, and Fridays in 6-120. The recitations will take place on Wednesdays at 4:05 pm and on Thursdays at 3:05 and 4:05 pm. The recitations will all be in 26-310, and will each be 50 minutes long.
I look forward to seeing you.
— Alan Guth —