Now, this is probably a very noob kind of question, but I am just going to say I just don't know how to answer this following series of questions. If we have a circuit, with a battery and bulb and the wires connected per normal, how do we physically explain the expenditure of energy in terms of the electrons of the current? Is the energy transferred from the electrons to the filaments in the bulb? If so, what kind of energy is expended? Kinetic energy of the electrons? If so, why doesn't the electrons reduce speed? Then would not the current be reduced? I remember playing around with a electric circuit simulator that seemed to imply that the electrons were "pushing" against one another...but I would like to have a more concise (mathematically, if possible) understanding of this conceptual problem I have. I understand current as being an average of the electrons passing through a cross-sectional area of the wire per unit of time....I hope that this is not the reason that I cannot comprehend this problem.