My son, who had been into biology and paleontology throughout middle school, is now veering suddenly towards physics. I've been bombarded with questions like "why do hot objects radiate light" and "what is electromagnetic radiation" and so on. Being an electrical engineer, I can handle most of these questions, or look up what I cannot, but it would be nice to buy him a book (or 5) for his upcoming birthday. Can you recommend any good books that he can handle? Obviously, the focus should be on concepts, rather than equations at this stage, but we did talk about the relationship between energy and frequency, and I showed him what Plank's constant is and so on. Subjects could be varied - I'm thinking thermodynamics and heat, atomic/quantum theory, and electricity/magetism could be topics that are accessible with the right treatment. Thanks!