classic light bulb problem | Golden Skate

classic light bulb problem

PolymerBob

Record Breaker
Joined
Feb 17, 2007
You are on the bottom floor of a house, and there are 3 light switches on the wall. Two floors up, there is an attic with 3 light bulbs. Each bulb is controlled by a switch downstairs. You have to determine which light switch downstairs controls which light bulb upstairs.

By the way, you can only climb the stairs once. :biggrin:
 
Can the light be seen from the bottom floor? If so, I would turn on 2 lights, get up there to verify the switch for the dark bulb. Then I'd take out one of the lighted bulbs or better and easier yet also the dark bulb. I could then go down to find the switch that would turn on the last light which is one of the two initially turned on. Voila.

Alternatively, I could turn on one light, unscrew it and another one, and go back down to find the switch for the last bulb.

If I can't see the light from downstairs, hmmmmm, still have to figure it out.
 
Last edited:
Here's my guess.

Turn two light switches on, leave one off. Wait a few seconds. Now turn off one of the two switches that are on. Go upstairs. The light that is on goes with the switch that is currently 'on'. That's an easy one. Now feel the two 'off' bulbs. The one that is cold goes with the switch that was always turned off. The one that is warm goes with the switch you turned on, then off.
 
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