I am an undergraduate with 3 more semesters left and with the majority of my physics core complete, except for quantum theory. I'd like to give my best effort to entering a top graduate school, but I got B marks in E&M I and Classical Mechanics. This semester was a turnaround, with straight A's, including E&M II (which I loved.) I think that getting an A in grad-level E&M could demonstrate that I know physics core well before entering a PhD program. Question is, how much would I risk getting a grade below an A with a good prof? And if I do switch into the grad-level course, could you please suggest which of these 400 level courses I can drop as the most "useless" for a serious physics student? - Theoretical Astrophysics II in the Astro department - Ordinary Differential Equations II with Stability Theory - Applied Partial Differential Equations.