Brainteaser-3 switches and alight bulb

[imhotepmp]

There is a closed room with a light in it. Outside, there are 3 light switches. You can flick any of the switches any number of times. You can only open the door and go into the room once. You know that the light is initially off. How can you determine which light switch operates the light?


Rules(To make it a little more difficult)
-You can not leave the door open
-You can not see under the door to see if the light is on.


anyone?

imhotepmp

 

[snow patrol]

Get your mate dave to stand in the room and bang on the wall when the light comes on.

 

[RSI]

snow patrol, you go in the room and I'll stand out here. When the light comes on, bang on the wall!

-RSI

 

[BigToque]

turn all of them on, and assume one of them works

 

[xero]

just flip each switch in the opposite position it's currently in.... say switch 1 is pointing down, you point it up...switch 2 is pointed up, you point it down...etc

you never said that couldn't be done.....you're bound turn it on then

 

[BigToque]

are all switches in the same position (eg, all down or up)?

 

[snow patrol]

I have sore, cold hands and will be partaking in no wall banging tonight matey

 

[Superwombat]

Remove the faceplate, check which light switch has wires going to it... if all three have wires, use a voltmeter to determine which are passing voltage. If all three match, cut all of the wires, then the answer is "none of them"

 

[DaveJ]

Flip the first switch on, leave it on for 10 minutes. Turn it off. Flip the second switch on, go inside and see which light is on. As for the two that are off, the one with the hot bulb is the one you left on, so it's controlled by the first switch. Hence, the last switch controls the one that is cold.

Dave

 

[damocles]

Thats close Dave, but i think there is only one bulb. So you flip switch 1 and leave it on for 10 minutes and then turn it off. Then turn switch 2 on.

Enter the room; To Determine which switch controls the light, do the following.

If the bulb is on, it is switch 2. If the bulb is warm, it is switch 1. If it is cold, it is switch 3.

 

[DaveJ]

Damocles: Yeah, that's exactly what I meant... Gotta get more sleep...

Dave

 

[imhotepmp]

exactly right damocles.

GJ!




imhotepmp