- Joined Feb 26, 2005
I am having a problem understanding voltage divider problems in my book. I understand, but don't know why voltage (pressure) is dropped when electrons go through a resistance. It seems that if it's harder for electrons to move through a resistance they would get backed up and the pressure behind would rise since there is a lot of voltage (push) behind, but the volume would fall (water analogy). Anyway, it's easy to figure just the voltage drops. What my problem is is when you tap off of the resistors. My book is showing voltage drop in one direction, but current flow in the opposite, which goes against all of the other problems in the book so far. It's a DC circuit. My other problem is that when you tap off of the resistors, as in my first figure it seems that you have now turned the circuit into a series-parallel setup which means if you start at the bottom with 300v some of the current goes through R1, and some goes through the circuit A at 300v. That would mean that there is a voltage drop through R1 and a voltage drop through the circuit A, and whatever is left joins at point B and then goes through R2 (90v dropped in R1 and what's left of the voltage in circuit A), then there is a voltage drop in R2 and what's left of the 300v in circuit B, etc. If you start at the top current would be going in the opposite direction from the figure, and the process makes more sense. Is the current direction in the book wrong? All of the other problems keep on showing current opposite of voltage too. I asked an engineer about the problem and he couldn't give me any good answer except that he thought the current direction is wrong. I also asked other people and they said that voltage does go in the opposite direction of current, which makes no sense to me since voltage is what causes current (electrons) to move. Also, how can you get a negative voltage? It seems if you've used up the voltage there can be none left.