For one of my physics classes (oscillations, waves, quantum mechanics) we use Young and Freedman University Physics 13th edition. However, the lectures given by the professor are usually more difficult/ on a higher level than the textbook. For example, right now we're learning about electromagnetic waves, Maxwell's equations, optics, etc. Most of the time the textbook just presents the formulas (Snell's Law, ratio of incident and reflected electric field, etc.) and says they can be derived from Maxwell's equations. I was wondering if anyone knew a textbook that went into more detail with the derivations of these formulas, seeing as our exams reflect that difficulty.