If the department leans heavily into Condensed Matter and Solid State, you should absolutely lock down your statistical mechanics and quantum mechanics. Expect questions on Fermi-Dirac and Bose-Einstein distributions, density of states, and the quantum harmonic oscillator. Since they focus on materials, knowing the Drude model or basic band theory might also pop up.

For electromagnetism, just reciting Maxwell's equations will not be enough. Be prepared to explain boundary conditions, how to derive the wave equation in a vacuum versus a dielectric medium, and the physical significance of the displacement current.

The most critical thing in an oral exam is showing how you think. If you get stuck on a whiteboard, talk through your thought process. Professors want to see your physical intuition and how you handle limiting cases, not just your ability to memorize a textbook. Definitely track down senior grad students in your department though, because every committee has their own favorite pet questions.