[mewminator]

2 rooms, one has 3 switches, one of these switches turns on a light bulb in the other room. how can you identify which switch turns on the bulb in the other room and you can only take one trip to that room.

N.B you cannot peak into the room, use any tools, ask for another's help ...etc

you may think there are only on and off as possibilities but think out of the box to create a third one (without ignoring the restrictions)

turn on one switch(s1) and leave it on for a while then turn it off then turn on another(s2)

IF:

it is on then it was s2

it is off then:

IF

it is hot :s1

it is cold:s3

[Guest]

turn on a switch for some time(say Switch 1).then turn on another switch(say Switch 2) and turn off the first switch.Go to next room

1. if the bulb is on then the switch for the bulb is current switch(Switch 2).

If the bulb is not glowing,touch the bulb

2 . if the bulb is hot then the correct switch is first switch(Switch 1)

3 . if bulb is not hot then the correct switch is the third one(Switch 3).

one problem If the bulb is fused then we cant find which is the correct switch.

[Guest]

I'll name the switch for easy explanation ... (S1, S2 & S3) I'm starting with my solution thinking that all switches are in OFF position.

Procedure : Switch "ON" S1 ... wait for few minutes then turn it off. Switch "ON" S2 and go to other room. If bulb is ON, the 2nd switch is the correct one, if bulb is still OFF, touch the bulb if its cold then the S3 (third switch) is the correct switch. If it's warm, then S1 it is.