Riddle Me This: The Three Light Switches

There are three switches in a basement. Each corresponds to one of the three light bulbs upstairs in the attic. You can turn the switches on and off and leave them in any position.

How would you identify which switch controls which light bulb, if you are only allowed to go upstairs once?

Answer: Light bulbs get hot, right? So let’s use that to our advantage! Turn on one of the switches long enough for the bulb controlled by it to warm up, then turn the switch back off. Flip one of the remaining switches on and leave the third one off. When you go to the attic, you’ll automatically know which switch the illuminated bulb belongs to, and you’ll know which bulb corresponds to the first switch you turned on, then off, based on which unlit bulb is hot.

Brilliant!