Physics 12  Waves, Quantum Physics, and Statistical Mechanics, 20142015
A fullyear introduction to the physics of waves, quantum
mechanics, and statistical mechanics, for students planning to major in
physics, astronomy, or related fields.
Physics
12a  Introduction to Waves, OctDec 2014.
Simulation of what gravitational waves produced by colliding black holes might look like.
Image courtesy Henze / NASA.
It goes without saying
that this page is under construction.....
Announcements:
 Congratulations! Amaze your friends with your knowledge of waves!
And have a great holiday; see you in 2015.
 PLEASE fill out a TQFR! And I welcome any constructive criticism on the class:
Ph 12a comment form (Anonymous).
 Instructor:
Prof. Alan J. Weinstein

Office 1: 260 Lauritsen; Mail Code: 25648; Phone: x6682
Office 2: 354A West Bridge; Mail Code: 10036; Phone: x2166
Email: ajw AT caltech.edu
I do not have regular office hours; email me!
 Prerequisites:

Math 1abc or equivalent (differential equations, complex numbers, ...).
Physics 1abc, or equivalent (mechanics, special relativity, electromagnetism).
 Lectures:
 Tuesdays, 10:3011:55, 269 Lauritsen.
Thursdays, 10:3011:55, 201 East Bridge.
Any changes will be announced well in advance. Please arrive on time!
 Textbooks for Phys 12a:
 There is no required textbook for this course!.
Because this is wellestablished material, there are many textbooks which
cover most of the material we will cover in this course.
Find the one(s) that you find easiest to read and understand!
Crawford, Waves (Out of print; free pdf download
here).
Most of the course presentation is based on this text,
but many students think it is too wordy and poorly written
(Others like it just fine!).
Georgi, The Physics of Waves
(free pdf download here,
used with permission). This is a relatively wellwritten text; it may not go into
sufficient detail in some topics.
French, Vibrations and Waves;
amazon;
note that there are free downloadable pdf versions on the web,
I don't know the legal status of them...
Hecht, Optics;
amazon.
This is a more advanced text with far more detail on optics
than we will cover in this course, and little introductory detail.
The Feynman Lectures, chaps 2136, 4751.
See also
Ph 12a notes by Adam Jermyn from 2011
(only available on the campus network).
 Class notes:
 PDF files below under "Handouts".
 Problem Sets:

Posted below on Thursday of each nonexam week, due in
the Physics 12c IN box
across from 264 Lauritsen
in class (10:30) on the following Thursday,
and returned to the Physics 12b OUT box
across from 264 Lauritsen
by the following Monday.
Solution sets will be posted on the web.
You are strongly
encouraged to check your work when it is
returned to you.
Problem sets are essential for mastering
the material in this class!
 Exams:

Midterm and final exams
during appropriate weeks of the term (5th and 10th).
Both will be takehome and ``limited" openbook
(only the text and class notes allowed).
The final exam will be comprehensive.
 Grading:
 Approximately 50% problem sets, 15% midterm,
35% final exam.
 Recitations:

Wed 2pm, Location: Downs 103
Matthew Heydeman;
matthew.heydeman AT gmail.com;
Office hours: Wed 34pm in 414 Lauritsen, following recitation.
Tue 8pm; Location: 269 Lauritsen
Ingmar Saberi;
isaberi AT caltech.edu;
Office hours: Tue 9pm, following recitation.
 Grader:

KungYi Su, kungyisu AT gmail.com,
Office hours: TBD, TBD.
 Extensions:
 OFFICIAL policy:
Work (the entire problem set)
will be accepted up to one week late at 1/2 credit,
no credit thereafter.
Please put a note at the top of your problem set if it is late.
 Students may request extensions
from the corresponding grader
(see emails above) a day or more in advance.
Extension requests are governed by the honor system.
 One extension (for up to one week)
is allowed without question (your silver bullet).
Please put a note at the top of your problem set
that you are using your silver bullet.
 Extension requests should be accompanied by a good excuse
(eg, physical or mental illness), and in principle
should be accompanied by a letter from a doctor or the dean.
 Please put late or extension problem sets in the
corresponding grader's mail box, and email them.
 Late papers make far more work for the graders, who have their
own set of pressures and deadlines as graduate students.
There is no entitlement to extensions, so please do not be demanding.
 Honor Code and Collaboration policy:
 Work is governed by the honor system.
 You may not use sources that contain the answer
to a problem or to a very similar problem.
 In particular, do not use solution sets
from previous years, or problem/solution books, at any time.
Exams and their solutions from past years are not to be used in any fashion.
 Discussion with others is encouraged,
but then you should go off alone and write it up;
the work you hand in must be your own.
 Mathematica may be used in problem sets,
or in exams for getting past some mathematical chore
(not for gaining knowledge of the physics).
It should never be necessary; it is much better to master
the mathematical analysis yourself without help from Mathematica.
If you chose to use Mathematica anyway, make sure you simplify
the result as much as possible,
so that it is easy to see what the math is telling you.
 Please attend class, and section meetings!
 Please ask questions of the TA's and the prof.
 Please clearly write your name, date, assignment number
on all of your assignments and exams.
 Clearly mark the problem numbers and answers.
 Please write as neatly as possible.
A human being is trying to read your work well enough to give credit!
 Feedback:
 I greatly appreciate student feedback; feedback prior to the
endofterm evaluations lets me modify the class to fit your needs.
If you want to send a comment about the course,
click here.
I also welcome any comments in person, by email to
ajw AT caltech.edu,
by campus mail, whatever you like.
Or, talk to your:
 Ombudsfolk:
 Ombudsfolk are student volunteers who
represent the students of each of the undergrad houses.
They collect suggestions, comments, complaints, etc,
and present them to the head ombudsperson
at periodic meetings (free lunch!).
Talk to your ombudsperson!
 Nikita Sirohi, nsirohi AT caltech, Ruddock
 Angela Gui, ygui AT caltech , Blacker
 Ankit Kumar, akumar AT caltech, Lloyd
 Jacob Abrahams, jabraham AT caltech, Ricketts
 Justin Leong, jleong AT caltech, Avery
 Yanbing Zhu, yzzhu AT caltech, Page
 Chris Dosen, cdosen AT caltech , Dabney
 Marco CruzHeredia, mcruzher AT caltech, Ricketts
Brief Outline of course, fall term:
Note that although the outline references chapters from Crawford,
other recommended texts work fine as well!
 Introduction, prerequisites, course outline
 Free Oscillations (Crawford Ch 1)
Simple harmonic motion; mechanical examples;
energy conservation; linearity and superposition; beats.
Systems with > 1 degree of freedom: normal modes; modal analysis.
 Continuous systems (Crawford Ch 2)
Transverse oscillations of a string;
classical wave equation; standing waves; wavenumber;
Fourier analysis: Fourier decomposition; initial conditions;
free/fixed ends; dispersion relations; sound.
 Forced oscillations, resonance (Crawford Ch 3)
Damping forces; the damped forced equation of motion; resonance;
driving forces; elastic and absorbtive amplitudes;
resonance curves; LRC circuits.
 Wave propogation (Crawford Ch 4)
Travelling waves: wave propagation; phase velocity; dispersion relations
for various physical systems; energy/power flux; impedance.
EM waves: in dielectrics; plasma frequency.
Refraction and Snell's law;
index of refraction; total internal reflection
 Reflection and transmission (Crawford Ch 5)
Reflection and transmission at boundaries: 3D EM waves; mechanical boundaries;
reflection for displacement and for force; optical applications.
 Wave packets (Crawford Ch 6)
Modulations, pulses, and wave packets: information transfer; localization;
Fourier integrals; Dirac delta function; complex Fourier transforms;
wave packet uncertainty; Gaussian wave packets; group velocity.
 Waves in 3D (Crawford Ch 7)
Poisson operator; separation of variables;
wave vector; travelling, standing, and evanescent waves; waveguides;
spherical radiation; radiation from accelerating charge;
Rayleigh Blue Sky Law.
 Polarization (Crawford Ch 8)
Polarization: linear, circular, elliptical polarization;
complex polarization vectors; polarizing filters; Malus' Law;
BraKet notation; polarization by scattering; Brewster's angle;
retardation plates; unpolarized light.
 Interference and diffraction (Crawford Ch 9)
Interference and diffraction: twoslit pattern; coherence;
interferometry; Huygen's principle; diffraction from apertures;
Frauenhofer diffraction; Fresnel diffraction; diffraction gratings
 Geometric Optics (Crawford Ch 9.7)
Not covered! I assume you got this in high school!
Review lenses, mirrors, telescopes, etc.
 Waves and Quantum Mechanics (Crawford Suppl)
A brief motivational intro to Phys 12b.
Not covered! Ph12b is next.
Handouts:
(Access to solutions are restricted to Caltech)
 Phys 12a Assignment 1 (pdf)
and solutions (pdf)
 Phys 12a lecture notes, week 1 (pdf)
 Phys 12a Assignment 2 (pdf)
and solutions (pdf)
 Neato fourier analysis applets:
PhET Fourier simulator
(and lots more PhET simulations), and
huber Fourier , and there are lots more.
 And here's a simple Python script for Fourier decomposition
 Phys 12a lecture notes, week 2 (pdf)
 Phys 12a Assignment 3 (pdf)
and solutions (pdf)
 Phys 12a lecture notes, week 3 (pdf)
 EXTRA problem (with solution) about the
LIGO seismic isolation stacks, and
LIGO_stack_TF.py python code.
 Phys 12a lecture notes, week 4 (pdf)
 Phys 12a Assignment 4 (pdf)
and solutions (pdf)

Video (28 min) of Shive demonstrating his torsional wave machine,
and discussing similarities between mechanical, electrical and acoustic waves,
from 1959.
 Phys 12a lecture notes, week 5 (pdf)
 Phys 12a midterm p.1 (instructions),
Phys 12a midterm full,
and solutions (pdf)
 Phys 12a Assignment 5 (pdf)
and solutions (pdf)
 Phys 12a lecture notes, week 6 (pdf)
 Phys 12a Assignment 6 (pdf) (problem VI.2 "fixed"),
and solutions (pdf)
 Phys 12a lecture notes, week 7 (pdf)
 Midterm grade distribution (pdf)
 Phys 12a lecture notes, week 8 (pdf)
 Falstad's Waveguide applet,
and many other cool Falstad applets
 Fun
Radiating charge PhET applet.
 Check Google Images for visualizations of waveguides, cavity modes,
radiating charges, dipole radiation, etc.
 Wikipedia article
on Wallace Sabine, the founder of the science of architectural acoustics.
 Chladni plate video on YouTube
 Wikipedia entry on superluminal group velocities and
Article referenced there.
 Phys 12a Assignment 7 (pdf)  DUE MONDAY DEC 1;
and solutions (pdf)
 Phys 12a lecture notes, week 9 (pdf)
 Phys 12a Assignment 8 (pdf) and
solutions (pdf). DO NOT HAND IN  just for practice.
 Phys 12a lecture notes, week 10 (pdf)
 Interference and diffraction applet from PhET,
nice multiple slit diffraction java applet and
more interference and diffraction applets.
 Notes on demos (scattering, interference, diffraction) (pdf)
 Phys 12a final exam page 1 (instructions) (pdf)
 Phys 12a final exam (pdf)
and solutions (pdf)
 Phys 12a course grade distribution (pdf)
 Congratulations! Amaze your friends with your knowledge of waves!
And have a great holiday; see you in 2015.
Last Updated: Dec 16, 2014
Alan Weinstein/ajw AT caltech.edu