I hope I am posting this question in the correct forum. I am in the second course in an upper level Electricity and Magnetism sequence (E&M II). We are using Griffith's Introduction to Electrodynamics as in the first course in the sequence. We covered chapters 1-3, 5, 7, and some of 8 in the first course; and I followed Griffiths well. In the second course, we have done chapter 4 and started in on chapter 6; and I am lost, completely. Griffiths is using so many "approximations" and hand-wavy explanations. Does anyone have suggestions for electricity and magnetism texts that are more concrete; or is the nature of the subject riddled with approximations that break down in new situations?