Lecture, three hours; discussion, one hour. Requisites: courses 1A, 1B, and 1C (or 1AH, 1BH, and 1CH). Corequisite: course 32. Photons, black-body radiation, photoelectric effect, uncertainty principle, Bohr atom, Schrödinger equation, hydrogen atom, and selected topics in atomic, solid-state, nuclear, and particle physics. P/NP or letter grading.