I am a high school teacher preparing to teach grade 12 physics for the first time in the fall. I can't quite understand this and it is really bothering me... In the textbook my school uses, it says that accelerating charges produce electromagnetic radiation, while charges moving at a constant speed do not produce EMR. I am having trouble understanding why this is the case. I feel like I might be having trouble because I'm not exactly sure what the term "changing electric field" means. Does an electron moving at a constant speed not have a changing electric field? If not, what qualifies an electric field as a CHANGING field as opposed to a static one?