I can't get my head around this: How can the current in a series circuit be unchanged by any amount of resistors? 1) I understand that there is only one path, and thus; 2) I understand that the charge isn't used up. BUT. If current is the charge passing a point per second, and resistors are something that 'resist' the charge or slow it down, how can the central question be explained? Let me explain my reasoning. Take a roundabout and 10 cars, one at the start line and the rest behind each other. Let's say that, when they begin moving, (no acceleration, just constant speed) 5 get to the half way line per second. If I throw in a speed bump a quarter of the way round, this will decrease the cars' speed, and so less cars will pass the half way line per second. The current is decreased? I've gotten myself thoroughly confused; can anyone explain this simply? Are my definitions wrong, or my analogy, or something?