Which switch corresponds to which light by visiting room only once?
Outside a room there are 3 separate switches (X,Y, and Z) that connect in some unknown order to 3 light bulbs inside the room.There are no windows in the room and the door is closed.
Is it possible to determine which switch corresponds to which light by visiting the room only once?
Mark the switches 1, 2, and 3.
Switch on 1 and 2, but keep 3 off. Wait a couple of minutes, switch off 2. Quickly enter the room, touch both lights which are off. The warm one corresponds to 2, the cooler one to 3, and the one that’s on obviously to 1.