1. Quantum II (PHYS 4410) Lecture 16 Hydrogen hyperfine structure HWK 5 is due today at 6PM. Physics Colloquium 4PM, Duane G1B20.

2. Physics Colloquium 4PM today, Duane G1B20 Prof. Robert Birgeneau, University of California, Berkeley “Superconductors: Old and New"

4. 150 A) Same as the electron sees. B is B (duh!). B) Opposite what the electron sees. C) Zero because it can’t act on itself. D) Zero because it does not move. E) None of these For the spin-orbit interaction, the moving electron sees the proton as a source of B-field. The B-field seen by the proton is:

6. 150 A) What a minute… we already did that. It’s the same B-field as for H SO. B) Of course, that’s a different B-field and I can explain why. C) If you say it’s different, well OK, but I don’t know where it comes from. D) ZZzzzz zzzz… The proton produces a B-field at the location of the electron, so there is a new term in the Hamiltonian:

7. 150 What is the direction of B from dl’? Biot-Savart: What is the direction of B after integration?