Ok, I have a Physics exam in two days (on DC circuits) and I've pretty much done everything I've needed to. However, I am anticipating a few difficult problem solving questions, so just in case I would like to clarify a few things: 1. Generally, if you had two or more sources of power supply (EMFs) in a circuit; how would you tackle the problem? Just a general formula or tactic would be appropriate? 2. With regard to the voltage symbol in an EMF, does it matter how many lines you have or do a certain amount of lines denote a certain amount of voltage. 3. This last question isn't really to do with problem solving, but rather, I've always wondered. In a DC circuit, does the current always travels from the negative side through a possible route and to the positive end of the power supply?