Insight · ★★☆☆☆ · ~5 min
Three Switches, One Bulb
Three switches, one bulb in a closed room, one trip inside. Find the right switch.
by MindYourPuzzle
A lateral-thinking classic — the answer is "obvious" only once you stop thinking about electricity.
You're standing outside a room with the door closed. On the wall in front of you are three identical light switches. Exactly one of them controls a single incandescent light bulb inside the room. The other two do nothing.
The door is shut, so you can't see the bulb from where the switches are. You may flip the switches as much as you like — but you may open the door and enter the room only ONCE, and after that you must correctly say which switch controls the bulb.
Can you always identify the correct switch — yes or no?
(Answer "yes" or "no".)
Hints