Veit Elser - Professor of Physics at Cornell University - Physics 2218: Waves and Thermal Physics

Spring

2024

The title of this famous book refers to the temperature at which paper spontaneously ignites.

Announcements

(1/21) This course has no Canvas site. All information, course materials, etc. are accessed through this site.
(1/21) My position on DEI.
(1/22) Some thoughts about learning physics.
(1/22) Why this course has no textbook.
(1/22) If you wish to meet about something other than physics or homework, say you are dealing with a difficult situation, send me an email and we'll arrange a time to meet in my office (PSB 426).
(1/22) I'm planning to keep my Tuesdays and Thursdays free this semester, because I'm under a deadline to finish writing my book Deconstructing the Energy Landscape by the end of May.
(1/25) I checked with your grader, Michael, and he will accept electronic homework submissions. There are some downsides of electronic homework. First, Michael will not be able to mark your work and help you see where you went astray (you'll have to do that on your own by reading the solutions). Second, you will have less preparation for the exams, which will involve writing on paper. For things like graphical manipulations of functions (problem 1, HW 1) it's good to have some practice without the tools provided by an electronic interface (which you won't have on an exam).
(2/5) Be sure to get the updated version of HW3 with three problems.
(2/7) Study hall on Tuesdays is now in 294A
(2/29) This is the kind of announcement you only get once every four years. Many, if not most of you did terribly on the prelim! Question 3 about the organ pipe was meant to be a freebie, a rehash of lecture 10. Are you even reading the lectures? Please read pages 10.7-10.10. You will find the answer to question 3 on page 10.10. Unless I see some improvement on the second prelim there are going to be many low grades in this course. Now is the time to reboot your brain. A good way to do that is to start reading the lecture notes!
(3/11) In response to a student request, Monday office hours have been moved one hour later, 3:30-5:30.
(4/22) I tested positive for COVID on Sunday and have to miss study hall today. Avinash will give the lecture today, and we'll see how I'm doing on Wednesday.
(4/25) HW 11, due May 1, was updated.
(5/2) At the May 6 lecture we will be igniting paper by raising the temperature of the air in an enclosed space to 506 Kelvin. The enclosed space is a cylinder with one wall that can be moved to compress the air adiabatically. When starting at room temperature, 300 Kelvin, how much of a volume change is needed to reach 506 Kelvin?
(5/2) I will have a 4-year-old assistant for the igniting-paper demo. When I ask the class how hot the air will get, one of you will raise your hand and say "super-mega hot".
(5/5) Here are some notes about a calculus identity we'll be using in the last lecture, which sadly is not covered in your math courses.
(5/6) If you're not submitting HW 12 electronically, there's a collection box on the counter of the Physics Department main office.
(5/7) There will be a review session Friday 2:00-3:00 in our lecture hall.

Course Information

prerequisites (not negotiable): mechanics, electromagnetism, special relativity (or enrolled in 2216), complex variables, multi-variable calculus
two prelims and one final exam
one homework assignment almost every week
grade: homework 40%, final 20%, prelims 2 x 20%
recommended text: Feynman Lectures on Physics, Volume I
lectures, homework assignments, and exams will be based on the lecture notes posted below

Syllabus

waves
thermal physics

Lectures

lectures usually follow the lecture notes below
if possible, read them before the date of the lecture
there will be in-class demos not covered in the notes
to stay engaged during lecture you are strongly encouraged not to take lecture notes
lecture dates are tentative and may have to be revised

1/22 torsional oscillator waves
1/24 wave equation: initial conditions
1/26 wave equation: boundary conditions
1/29 co-ax waves
1/31 co-ax circuit model
2/2 co-ax wave equation, symmetry principles
2/5 symmetry transformations
2/7 wave equation in moving frame
2/9 electromagnetic waves
2/12 normal modes
2/14 water-surface waves
2/16 energy in water-surface waves
2/19 capillary waves, dispersion relation
2/21 review
2/28 superposition, Gaussian wave packets
3/1 uncertainty relations, phase & group velocity
3/4 wave dynamics and the Fourier transform, part I
3/6 wave dynamics and the Fourier transform, part II
3/8 phasors
3/11 model of waves in a gas (sound)
3/13 energy of a gas
3/15 sound waves in two dimensions
3/18 bulk modulus, sound waves in three dimensions, mean-free-path
3/20 wave propagation at an aperture
3/22 wave diffraction, reflection and transmission
3/25 diffraction with phasors
3/27 review
3/29 energy flow in waves on a string
4/8 energy flow in sound waves
4/10 energy flow in electromagnetic waves
4/12 wave reflection and transmission at an interface
4/15 wave refraction and Snell's "law"
4/17 thermodynamic equilibrium, random walks, sound dissipation
4/19 microstates, ergodic hypothesis
4/22 counting microstates
4/24 counting gas microstates
4/26 counting the microstates of a solid, gas-solid equilibrium
4/29 entropy, definition of temperature
5/1 thermal energy, equipartition, thermal equilibrium
5/3 system of magnetic moments in a magnetic field, negative temperature
5/6 ideal gas law from first principles

Exams

prelim 1: 2/22 7:30pm RCK 115 solutions
prelim 2: 3/28 7:30pm RCK 115 solutions
final: 5/11 2:00pm RCK 231

Mathematica computer demos

Homework (bring to class on date next to each assignment, or submit electronically before class)

Staff information

lecturer: Veit Elser (ve10), office: PSB 426, office hours: Monday 3:30-5:30 pm, Clark 294F
TA: Avinash Mandaya (am2957), office hours: Tuesday 2:30-3:30 pm, Clark 294A; Friday 2:30-3:30 pm, Clark 294H
grader: Michael Kaemingk (mk2533)