I have a problem understanding the concept of potential difference. I get the picture of seeing it as a height difference for example (rock or water that would fall down) but what confuses me is that many times the order of elements in a circuit does not matter. To explain myself better: if I have a battery, an Led and a resistance, no matter if I put the resistance before or after the led, always the same amount of current will flow because what matters is that the resistance has now added another potential drop. This is a bit esoteric to me since is like saying that, though no current is flowing, this different potential is already there. I can see a potential difference as a force which is due to charges that are accumulated for example in a battery but what happens at the charges level when the resistance is added? I get that in the intuitive picture of the height difference this would be like lowering the top of the mountain or placing the valley higher but what happens physically at the level of charges? There are ten electrons and ten holes at the two poles of a battery, if I add on one side a resistance, would the charges move to it which means that on the other extreme now I might have only 5 charges (due to the effect of the resistance) and therefore when I close the circuit now I will have less charges moving? But if this would be the case, then a current is flowing even when the circuit is not closed which is not possible, so my idea is not correct. Any idea of how could I visualize this more practically since the similarities with mountains and rocks don't work for me? Thanks a lot!