You are standing in front of a room with one light bulb inside of it,you cannot see if it is on or off. Outside the room there are 3 switches in the off positions,you may turn the switches anyway you want to, you stop turning the switches, enter the room and know which switch controls the light bulb, How?

Hint: consider using senses other than sight alone.

Maybe process of elemination, you find 1 switch controls the fan, 1 switch controls the fan light, and 1 switch does nothing you can see. I would guess that to be the bulb?

Maybe process of elemination, you find 1 switch controls the fan, 1 switch controls the fan light, and 1 switch does nothing you can see. I would guess that to be the bulb?

In this riddle there is no fan. Only one light in the room, controlled by one of three switches located outside the room and the door is closed. You're allowed to manipulate the switches any way like, then open the door and walk in and observe the state of the light. If you know that only one of the switches operates the light, how do you determine which one it is?

Another hint: you can take several minutes to operate the switches before opening the door. And the technique works well if the light bulb is the old fashioned incandescant type, but may not work so well for CFLs or LED bulbs. OK, that's enough hints for now.

I was thinking you could hear the load on the switch contacts, problem is the other 2 switches could also switch light bulbs and make the same sound, And if in a dark room, you may be able to see a flash or momentary glow? Is is assumed the other 2 switches have no load?

Let's assume that two of the switches operate something else - but not the light in the room and not something close by that you can observe.

Turn switch one on for a period. Turn switch one off and switch two on and enter the room. If the light is on then switch two. If light is off then feel bulb. If bulb is warm then switch one, if bulb is cold then switch three.

I would say you got it HK.

I would say you got it HK.

Yes he did!

Each switch would have to do something. So, one switch would turn on the light you wanted to turn on. The other two, you could see if they did something else. So even if you don't know if the light is on or off, you can tell what the other switches do and process of elimination, you have your switch!

mmhdcat,
Unless 1 switch was for a switched outlet and nothing was plugged in, not to mention outside lights?

The riddle says that there are 3 switches. Doesn't say that they do anything other than implying that one turns the light on.
It's a riddle, intended to make you think. Its pretty obvious with;


Hint: consider using senses other than sight alone.

It's a riddle, just a riddle