1. The problem statement, all variables and given/known data As contact point Y moves to X, the lamps becomes brighter. Why is this so? 2. Relevant equations R=p (length/Area) I=V/R 3. The attempt at a solution As Y moves closer to X, length of wire decreases, hence resistance decreases and brightness of lamp increases. I am not clear of the concept of brightness of lamp and resistance of wire. Please help, thank you!