i would like to know the underlying reasoning why it works the way it does and how it works based on the explanation given by the book Electricity Demystified, but i would like a far better explanation. Give me something like an analogy to better explain it physically. In there it says: for voltage sources in series: E = E1 + E2 + E3 + ...+En (all connected "minus to plus" with polarity reversal: it is E = E1-E2+E3+...+En (reverse the polarity of battery number 2 with voltage E2) for voltage sources in parallel: in a parallel circuit, the poles must all go "plus-to-plus" and "minus to minus" the output voltage of a properly designed parallel combination of cells or batteries equals the voltage of any single one of them. (i think this is due to kirchoff's voltage law). i would like a of this schematic/drawing of this circumstance. I=I1+I2+I3+...+In I have to understand this logically to progress through.