# which switch corresponds to which light bulb?

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You are standing outside a closed door. On the other side of the door is a room that has three light bulbs in it. The room is completely sealed off from the outside. It has no windows and nothing can get in or out except through the door. On the outside of the room there are three light switches that control each of the respective light bulbs on the other side of the door.

Your assignment is to determine which light switch controls which light bulb. You are allowed to enter the room only once, and once you come out, you must be able to state with 100% certainty which light switch controls which light bulb.

posted Jun 16, 2016

+1 vote

You flip the first switch and wait several minutes.
Then you flip the first switch again, flip the second switch and look at the lamp.
.
If the lamp is off but warm it is the first switch.
If the lamp is on, it is the second switch.
If the lamp is off and cold it is the third switch.

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