PHYS 406: Electricity and Magnetism II

Instructor
Prof. Francis-Yan Cyr-Racine
Email: fycr@unm.edu
Office: PAIS 3214

Teaching assistant
Kylar Greene
Email: kygreene@unm.edu
Office: Zoom


Description of the class

This class builds on the foundation established in PHYS 405 to develop the complete theory of electrodynamics. Starting from Maxwell's equations for electrostatics and magnetostatics, we will see how these have to be modified to account for time-varying fields. Equipped with the time-dependent Maxwell's equations, we will be able to discuss the energy, momentum, and angular momentum contained within the electromagnetic field. We will then discuss the very important topic of electromagnetic waves and their propagation both in vacuum and within linear media. We will then argue that scalar and vector potentials are generally easier to handle than fields in electrodynamics, and will use this fact to compute the E&M signatures of moving point charges, including how they radiate energy in the form of electromagnetic waves. We will finally turn our attention to more fundamental aspects of electrodynamics, discussing its relativistic nature and its modern Lagrangian formulation, which reveals the fundamental symmetries underpinning the theory.


Syllabus

The detailed syllabus can be found here.

Lectures

Tuesdays and Thursdays, 12:30-1:45pm in PAIS 1140.

Textbook

Textbook for the class
Introduction to Electrodynamics (5th Edition) by D. J. Griffiths. Older editions of the book are fine as well. The course will cover Chapters 7-12.

Additional resource
Electricity and Magnetism by E. Purcell and D. Morin.

Office hours

Instructor
Tuesdays and Thursdays 10:00-11:00am at my office. These are my preferred "office" hours. If you can't make my regular office hours, or if your questions cannot wait, please send me an email to set up an appointment.

Teaching assistant
The teaching assistant is Kylar Greene (kygreene@unm.edu). He will be available on Tuesdays 3:30-4pm on Zoom for you to meet and discuss any homework grading issues you may have. If you need to schedule an appointment outside of the TA's office hours please send him an email.

Grading

The grading in the course will be based on your performance in homework assignments, two midterm exams, and a final exam. The contribution to the final grade is as follows:

  1. Class participation will be 10% of the final grade.
  2. Homework: 9 assignments will represent 20% of the final grade.
  3. Two midterm exams: each of them will represent 20% of the final grade.
  4. Final exam: will represent the remaining 30% of the final grade.

The midterm exams are tentatively scheduled for September 19th and October 24th during class time, and the final exam will be held during exam week.

Homework assignments

There will be 9 assignments during the semester. The assignments will be posted in the tentative schedule about 7-10 days before they are due. The login information necessary to access the homework PDFs will be provided in the first class. The homework must be submitted on UNM CANVAS by 7pm the day they are due. No paper copy will be accepted. Late homework policy: homework returned in the next 24 hours after the due date will be accepted but with 25% penalization (i.e. the maximum grade you can get in this case is 75% of the total points for that homework). After these 24 hours the corresponding solutions will be posted here, and homework assignments submitted after solutions post will not be graded.

While I strongly encourage you to discuss the homework assignments with your classmates, the work you hand in must be entirely yours.

Problems class

Listed officially as PHYS 416, this is a very important adjunct to the main lecture class, taking place every Wednesday from 1 to 1:50pm in PAIS 1140. It will provide you additional practice with solving problems beyond the homework assignments and self study. Furthermore, the class will also give you a valuable opportunity to bring to my attention your difficulties with any concepts covered in the lecture class so I can address them in a group setting. The problem sheets would be posted here on the Wednesday before the problem class. The corresponding solutions will be posted after the class. You will receive credit for the problems class as long as you register and show up for more than 10 sessions. Even if you don't register for the class, I encourage you to attend anyway, just to get the extra practice.

Tentative schedule


Date Lecture Notes Griffiths Reading Homework HW Due Solutions
Week 1
08/19-08/23
Review of Electro- and Magnetostatics
Vector potential example
Chs 1-6

Homework #1
09/03
Homework #1 Solutions
Week 2
08/26-08/30
Current, EMF, and Faraday's law
Ch. 7.1-7.2



Week 3
09/02-09/06
Inductance and B field energy
Matter effects in electrodynamics
Ch. 7.2-7.3
Homework #2
09/10
Homework #2 Solutions
Week 4
09/09-09/13
Poynting theorem, energy and momentum
Momentum conservation in electrodynamics
Ch. 8.1-8.2
Homework #3
09/17
Homework #3 Solutions
Week 5
09/16-09/20
Review of Chapters 7 and 8
09/19: Midterm #1
Chs. 7-8


Midterm #1 Solutions
Week 6
09/23-09/27
Intro to electromagnetic waves
Energy and momentum of E&M waves
Ch 9.1-9.2
Homework #4
10/01
Homework #4 Solutions
Week 7
09/30-10/04
Electromagnetic waves in matter
Brewster's angle
Ch. 9.3-9.4
Homework #5
10/08
Homework #5 Solutions
Week 8
10/07-10/11
E&M Waves in conductors
Reflection on conductors
10/10: No class (Fall Break)
Ch. 9.4



Week 9
10/14-10/18
Dispersion
Dispersion of Gaussian wave packet
Wave guides
Rectangular wave guide
Ch. 9.4-9.5
Homework #6
10/22
Homework #6 Solutions
Week 10
10/21-10/25
Energy propagation in wave guides
10/24: Midterm #2
Ch 9.5


Midterm #2 Solutions
Week 11
10/28-11/01
Potential formulation
Retarted potential
The potential from a moving point charge
Ch. 10.1-10.2
Homework #7
11/07
Homework #7 Solutions
Week 12
11/04-11/08
The E and B field from a moving charge
Ch. 10.3



Week 13
11/11-11/15
Four-vectors and metric
Lagrangian for a relativistic particles
Ch. 12.1
Homework #8
11/21

Week 14
11/18-11/22

Electromagnetic Lagrangian and the Lorentz Force
Ch. 12.2-12.3



Week 15
11/25-11/29


11/28: No class (Thanksgiving)
Ch. 12.2-12.3
12/05

Week 16
12/02-12/06






Problems class


Date Problems Solutions
08/23
Problems #1
Problems #1 Solutions
08/28
Problems #2
Problems #2 Solutions
09/04
Problems #3
Problems #3 Solutions
09/11
Problems #4
Problems #4 Solutions
09/18 Review Midterm #1
Review Midterm #1 Solutions
09/25
Problems #5
Problems #5 Solutions
10/02
Problems #6
Problems #6 Solutions
10/09
No Problem class (Fall break)

10/16
Problems #7
Problems #7 Solutions
10/23
Review Midterm #2
Review Midterm #2 Solutions
10/30
Problems #8
Problems #8 Solutions
11/06
Problems #9
Problems #9 Solutions
11/13
Problems #10

11/20 Problems #11

11/27


12/04