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Attic Light Switch

A downstairs panel contains three on-off switches. One of them controls the lamp in your attic. Using only ONE trip up to the attic, how do you determine which switch controls the lamp?

see explanation

Turn on the first switch and leave it on for a few minutes. Turn on the second switch and go to the attic. If the lamp is on, the second switch controls the lamp, if you touch the lamp and it is warm, the first switch controls the lamp, otherwise, the third switch does.



Or just realize that the other two switches are for lights on the main floor and so determine which one is correct by process of elimination..


Turn on one of the switches, since you are downstairs, see if any thing happens, do that with all the switches until one of them doesn't react with anything, downstairs.

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Submitted by
about 4 years ago
Difficulty 4.7 ?

brain teaser reasoning