I have an upcoming Physics exam and I just want to make sure I want to understand the concepts in case they throw something unprecedented at us: Can someone please check if the statements I made are right because I'd really like to have a thorough understanding of this concept. It's sometimes the smallest things that get to me in an exam. ~DIRECT CURRENT~ If two light bulbs are connected in series, and one side near the positive end of the supply source is open, all three bulbs will function right if they are a direct current? If two light bulbs are connected in series, both of them will exhibit the same amount of brightness assuming that they bear the same resistance. If two light bulbs are connected in series and three are in parallel, then the two in series will obviously be brighter right, whilst the three connected in series won't be because of the fact that they do not have as many electrons flowing in them? What primarily determines the brightness of the light? Is it the current or the voltage?