257 replies to this topic

[rookie1ja]

Don't know if this solution is already posted before...

the correct solution is in the very first post ... and in hundreds of posts after it

[jreichart]

Why wouldn't you just turn on 2 switches, enter the room and make note of which lights are on, then unscrew one bulb. Go back to the switches and alternately turn on/off the switches you had already turned on. The one that does nothing controls the light with the loosened bulb, and the 2nd switch controls the other light that was on. You know the switch you didn't touch controls the light that was not on at all. Problem solved, and no burned fingers!

[Greg Arnold]

I believe that my answer works, although it differs from the given answer: I would turn the 1st switch on. Eventually it would burn the bulb out. Let's allow 2 weeks of "on" to assure this occurs. Then, I turn on switch 2. Lastly, I go into the lamp room and observe which bulb has a broken filament (1), which bulb is on, and bulb which is off. - Greg Arnold

[new guest]

greg arnold, you are very smart. i would tun the bulb off though, just to make sure.

[RCool7]

Just turn on one for a while for at least 2mins and hen turn it off and turn another on and go into the room. The light that is on will be the switch that is on and the warm bulb will be the first switch and obviously the last switch is to the cool and unlit bulb. This is one of the easier ones I've seen.

[the new riddler]

this is an old one...
turn on 1
wait ten min
turn off 1 and turn on 2

go in
if bulb is hot, it's 1
if on, its 2
if off and cold, it's 3

[i am a liar]

guys what if the bulb is is too high to touch

[RajPath]

Sequence of steps are given below:

Switch 1: ON: Leave ON for 10 minutes: OFF
Switch 2: ON
Go to room with bulbs
1 bulb will be glowing: This is linked to Switch 2
Check which bulb is hot: This is linked to Switch 1
Check which bulb is cold: This is linked to Switch 3
Voila !!

[buddhabuddy87]

1)Switch 1 (turn on for 5 minits turn off again)
2)Switch 2(leave on)
3)Do not touch switch.
walk into Room if bulb is on it's switch 2 if it's off and hot to touch then it's switch 1 if it's not hot switch 3

[Jordanmax]

Bulbs - Back to the Logic Puzzles
This is one of my favorite logic puzzles (Edit: it is more a practical than a logic puzzle).
Imagine you are in a room with 3 switches. In an adjacent room there are 3 bulbs (Edit: let's say in lamps which are on a regular table) - all are off at the moment, each switch belongs to one bulb. It is impossible to see from one room to another. How can you find out which switch belongs to which bulb, if you may enter the room with the bulbs only once?

Edit: No help from anybody else is allowed.
Edit: Find out which switch belongs to which bulb - identify all 3 switches (so find out what bulbs are switches 1, 2 and 3 connected to)

turn one on for a while. Then turn it off turn another one on. Enter the room see which one is hot. then there is one on and one cool.