1. The problem statement, all variables and given/known data 2. Relevant equations None 3. The attempt at a solution The answer is B, bulb B will be brighter than before. My thought was that initially, the current gets split so that 2/3 I0 goes to the branch with 2 bulbs, since it has twice the resistance of the first branch, and that 1/3 I0 goes to the first branch. And when the switch is closed, that initial junction doesn't change, so I picked D. Can anyone explain where I went wrong?