PHYSICS 355 - Rory Coker
Prof. Rory Coker
Office: RLM 8.312
Phone: (512) 471-5194 (not recommended)
Fax: (512) 471-9637 (not recommended)
Email: rory coker's civilian mail, coker's physics department mail

Office HoursThur, 2 - 3 PM, every week.
Tue 3 to 4 PM, in PMA 8.312, on days when there is a Pizza Seminar. 

[S] [A] [OK] [F] [T] [KC] [T] [T2]

The Spring 2024 unique number is 56080; the class meets 12 noon to 1 PM in PMA 5.104. Attendance is EXPECTED in class.   If you need personal help with the homework and are on campus, the Coaching tables by the elevators on the 5th level of RLM Hall will be manned, according to the coaching schedule, regularly on weekdays. When you are on campus you can get instant help with homework and get more explanation of concepts. Course TA: Joshua Ziegler, office hours Wednesday at 11:00 AM and Friday at 3:00 PM, PMA 9.318. He will also respond to e-mail questions.

Text: Modern Physics from α to Z0 by James William Rohlf. There are free pdf and other versions of this book in several places on the internet, and used book dealers sell it for $15 to $25, depending on condition. Four copies are on reserve in the PMA Library. Recent modern physics texts sell for up to $200, and they differ only in the last chapter when compared to books published 20 years ago.

Background information: The physics department offers the following upper-division undergraduate physics courses, which extend and detail concepts briefly surveyed in 355--- 362K, atomic and molecular physics; 362L, nuclear and particle physics and astrophysics; 369, thermodynamics and statistical physics; 373, quantum physics. In this course you should begin by reading Chs. 1, 2 and 3 in Rohlf for historical background. The course lectures will begin with Ch. 4 on special relativity.

Syllabus and first day handout. Basis of course letter grade: Homework, 60%; midterm exam, 25%; class attendance, 15%. Class attendance is NOT OPTIONAL; it is expected, and contributes a significant percentage of the overall course grade. See the course syllabus for more details.

Useful Online Resources: Relativistic Dynamics

Class Notes: Special Relativity, Uncertainty, Scattering

Class slides: Visual Relativity! Matter Waves! Uncertainty! Scattering Experiments! Schrodinger Equation! Hydrogen Atom! Atoms! Molecules! Nuclear Physics! Nuclear Processes! Statistical Physics! Lasers! Scattering of Light! Condensed Matter! Superconductivity 1, Superconductivity 2, Accelerators! Particles! THE EIGHTFOLD WAY! Interactions! Coupling and Mass!  Astrophysics!

ANSWERS TO IN-CLASS ATTENDANCE QUIZZES: (1) The observer measures a smaller volume for the cube moving past.  In its proper frame it has V = L3. But in the observer's frame of reference the length parallel to the velocity is L', which is shorter than L. So V' = L2L', which is smaller than V.  (2) For Q, Δx is very small so Δpx must be very large. For R, λ (and thus p) are well defined, so Δx must be very large.  (3) No matter how high the kinetic energy of the beam particles, so no matter how small the wavelength of the associated probability amplitude, the objects scattering the wave still appear pointlike.  (4) A notation like 3p3 means nℓ#, in other words n = 3, ℓ = 1 and 3 electrons in the state.  (5) Simple molecules absorb mainly in the infrared (vibrational transitions) and microwave (rotational transitions).  (6) These are various isotopes of Pb, all being chemically the same (same number of protons and electrons) but differing in the number of neutrons.  (7) About 85% of the ionizing radiation received by the average person in the US comes from diagnostic X-rays and radioactive gases in the air inside buildings.  (8) Just to break even, a d-t fusion reactor needs to operate at a temperature of a billion Kelvin, in both magnetic and inertial confinement approaches.  (9) Sooner or later any excited state in a quantum system of charged particles will de-excite, generally by emission of a photon.  The only stable state is the ground state.  [Sometimes, of course, another process, like collision with another system, might de-excite the system before it can radiate a photon.]  (10) NaCl is the classic example of a crystal held together by the ionic bond... Na loses an
electron and Cl gains it.  The crystals are cubic because the atomic lattice is cubic.  (11) Type 2 superconductors can remain superconducting in enormously strong magnetic fields, type 1 superconductors cannot.  (12) A proton is a fermion, a hadron and a baryon.  It is not a boson.  (13) When a blue quark emits a blue-antired gluon, the quark becomes red.  (14) The Higgs Field gives mass to certain fundamental point particles, such as leptons, quarks and the bosons of the weak interaction.

MIDTERM EXAM RESULTS: Average 81, 15 students made grades of 100 to 90, 14 students made grades of 85 to 80, 8 students made grades of 75 to 70, 4 students made grades of 65 to 60, and 2 students made grades of 55 to 50.

  • HW 1, average grade 87%, 12 students made 100%, 5 got 65% or lower, 9 did not turn in HW.
  • HW 2, average grade 91%, 6 students made 100%, 3 got 70% or lower, 9 did not turn in HW.
  • HW 3, Average grade 89%, 6 students made 100%, lowest grade 70%, 10 did not turn in HW.
  • HW 4, Average grade 91%; 13 students made 100%. 4 students made 70% or below and 8 students did not turn in HW.
  • HW 5, Average grade 89%; 6 students made 100% . 6 students made 75% or below. 
  • HW 6, Average grade 86%; 5 students made 100%.  4 students made less than 65%, and 3 students did not turn in HW.
  • HW 7, Average grade 88.5%; the lowest grade was 72%.  2 students did not turn in HW.
  • HW 8, Average grade 83.6%, 3 students made 100 %. 5 students made 70% or below.  1 student did not turn in HW.
  • HW 9, due on April 10.
  • HW 10, due on April 17.

  • Here is a way to get extra credit!

    Here is the Golden Rule of physics problem-solving. Ignore it at your extreme peril.

    How to get involved in Undergraduate Research.


    COACHES AND TUTORS: Coaches are present at tables by the elevators on the 5th level of RLM, at various times between 9 AM and 5 PM weekdays. Coaches are there to give you hints on homework problems, and mini-lectures on key concepts in basic physics. A fairly accurate online resource on basic physics is here. 

    RELEVANT CLASS NOTES FROM 317L: Ch. 33, Ch. 34, Ch. 35, Ch. 36

    CLASS SLIDES FOR 317L and 303L (worked examples are often linked to these pages): Relativity 1, Relativity 2, Twins! Length Contraction! Binding Energy, Einstein's Theory of Gravity, Ch. 34, , Ch. 35, part 1, Ch. 35, part 2, Ch. 36, part 1, Ch. 36, part 2, Ch 36, pt 3, Ch 37, pt 1, Ch. 37, pt 2, Ch. 38, pt 1, Ch. 38, pt 2, Nuclear Decays, Radiation, Fission and Fusion, Ch 39, pt 1, Early Universe,

    CLASS SLIDES FOR OTHER CLASSES:  The Dark!  Deuteron, Then and Now, Dark Matters!  Where is it?  Atomic forces,  Waves, Reflection, Superposition, Standing waves on rope, Group velocity, Wave Applets, Fathers of the Wave,  Doppler effect,  Diffraction.

    How to open a corked bottle of wine with just your shoe and a wall.

    Max Planck

    Albert Einstein