1. The problem statement, all variables and given/known data A student finds that a set of Chrismas-tree lights do not operate when the switch is turned on. What is the most likely cause of this? 2. Relevant equations none 3. The attempt at a solution There could be a hole somewhere along the circuit. There could have been a short circuit. But wouldn't that lead to an explosion of some sort? The switch isn't working. There could be many possibilities but don't know which is most likely.