BrainDen.com - Brain Teasers

# Bulbs

## Recommended Posts

Assuming that there is a pathway between the switches room and the bulbs room, I would first turn on 1 switch, then go to the room and out of the 2 OFF bulbs, I would remove one bulb. I would go back to the switches room, first turn OFF the ON switch, then turn ON 1 of the remaining 2 switches and check through the pathway if the room is lit. If the room is not lit, then you know that switch is linked to the bulb that you took out.

##### Share on other sites

I GOT THE ANSWER FOR SURE...DONT LISTEN TO THE OTHER GUYS BEFORE ME.

Assuming that these bulbs are incandescent.

First I would turn on the first switch and keep it on and wait ten minutes.

Next I would turn on the other switch and leave the other switch Off,

and run upstairs right away, the first bulb I turned on has been on for at least over 10 minutes,

So I know that bulb is hot and I know it goes to the first switch I turned on for sure.

And the one I just turned on is cool so I know it goes to the second switch I turned on.

And the one I left off goes to the switch I didn't turn on.

Piece of cake guys.

##### Share on other sites

Well this is not difficult. First of all i give number to the switches. Number one, two and three. Turn on number 1 for a minute. Turn number one off and inmediately turn on number two. I go the the next room and the one that is on is number two. Touch one of the other two bulbs and if it is warm, that is number one and the other is number three. If it is cold, that is number three and the other is number one. Does that sounds logic?

##### Share on other sites
Well this is not difficult. First of all i give number to the switches. Number one, two and three. Turn on number 1 for a minute. Turn number one off and inmediately turn on number two. I go the the next room and the one that is on is number two. Touch one of the other two bulbs and if it is warm, that is number one and the other is number three. If it is cold, that is number three and the other is number one. Does that sounds logic?

Yeah, I guess that sounds logic.

##### Share on other sites

switch on the first and second. wait one minute, then switch off the second. when you enter the room, the bulb still on is the first switch, the bulb that is warm to the touch is the second, and the final is the third.

##### Share on other sites

Unscrew 2 of the bulbs, and work out which switch turned on the remaining bulb. Then unscrew that one, and replace one of the others, and so forth...

Interesting.

##### Share on other sites

Can't you just leave the bulbs on? Alternate solution: Turn on 1 bulb, leave it on, walk into the room, then you can ID the two other bulbs easily.

##### Share on other sites

You don't need to enter the bulb room just peak your head in from outside when you want to see which bulb corresonds to the switch you turned on from the other room. I assume there is an entry because your allowed to enter the room once

##### Share on other sites

Number each switch 1, 2 and 3. Leave the first one off. Turn on 2 and 3 for about a couple hours or more. Just before entering the lighted room. turn off number 2. Once in the lighted room the two off light bulbs is therefore:

off cold is 1, off hot is 2 and so 3 is on.

##### Share on other sites

turn one switch on for about a minute, turn it off and turn the second switch on. Enter the room, the light that is on is obvious. the light that is off but still warm is the first switch.

##### Share on other sites

Turn on two switches and leave them on for several minutes. Then turn off one of the two switches. Walk into the bulb room an you should find 1 bulb on and two bulbs off. One of the two bulbs that are off should be hot, this bulb belongs to the switch you had on and then turned off.

##### Share on other sites

No one said that the switches couldn't be dimmer switches. You could also turn on more than one bulb at a time. 1 dim 1 bright 1 off, maybe?

##### Share on other sites

well i would turn the switch in the middle on (i figure the electrician wouldnt go through the trouble of mixing and crossing wires.) And if the middle switch turns n the bulb in da middle than most likely the other switches turn on the bulb in that order.

##### Share on other sites

you turn 2 switches on. make a note of which 2 you turn on. go in the room unscrew one of the light bulbs. go back in the room with the switches. turn of the switches one at a time. the one that turns the light off will be the one you didnt unscrew. the one that has no effect is teh other one you turned on. and of course the one that never came on is the switch you never turned on.

##### Share on other sites

you turn one on and let the bulb get hot then turn it off that is number one, then you turn the second switch on and leave the other off/ when you enter the room withthe bulbs the one that is hot is 1 the one that is on is 2 and the one that is off and cold is 3

##### Share on other sites

First switch on one of the bulb so as to know which one is glowing then put it off.

Secondly put ON another switch quite for long & put it OFF.

Now we can rack out which one is which. We'll feel hot for the second bulb as it's heated for long, for the other bulb which's not glowing it'll be cold only & for the first one we've identified at the beginning.

Hehe hehe, so simple...

##### Share on other sites

by simply switching on one switch you will find a bulb that lights up matching it. Since I chose to switch on the switch that I did, problem solved. You didn't want me to find all the switches matching bulbs, so therefore I found one to answer the child-ish teaser...

##### Share on other sites
by simply switching on one switch you will find a bulb that lights up matching it. Since I chose to switch on the switch that I did, problem solved. You didn't want me to find all the switches matching bulbs, so therefore I found one to answer the child-ish teaser...

I hope the following edit satisfies you:

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)

btw, have you solved the puzzle as I meant it?

##### Share on other sites

Here is what I would do:

First, flick two switches to turn on two bulbs in the room. Second, go into the room and unscrew one of the lit bulbs. Third, go back into the switches room and, one at a time, flick each of the two switches you had turned on to its off setting. The switch that turns off the light still lit in the room belongs to that bulb. The other switch belongs to the bulb you unscrewed. And that only leaves the last switch which, of course, always belonged to the bulb that was never lit in the first place.

##### Share on other sites

i think that if you turn two of the bulbs on and wait for a few minutes till they get hot and then turn one of them off, you will be able to go in the other room then, burn your hand and discern the difference between the two bulbs that are currently off.

##### Share on other sites
Here is what I would do:

First, flick two switches to turn on two bulbs in the room. Second, go into the room and unscrew one of the lit bulbs. Third, go back into the switches room and, one at a time, flick each of the two switches you had turned on to its off setting. The switch that turns off the light still lit in the room belongs to that bulb.

Welcome to the boards, blimmy. The problem with your solution is that you won't know if that switch turns off the bulb that's still lit because the riddle states "it is impossible to see from one room to another" and "you may enter the room with the bulbs only once".

##### Share on other sites

Three switches -- Turn two of them on and let them burn for 10 minutes. turn one of the two off. Go into the room. One is on, one is off and hot, one is off and cold. BINGO!

##### Share on other sites

Simply turn on one of the switches and leave it on for about 5 minutes to give the corresponding bulb a chance to get hot. Turn this switch off and then turn on one of the other switches. When you enter the room with the bulbs there will be the following:

1) One bulb on - corresponds to the last switch you turned on

2) One bulb off & cold - corresponds to the switch you didn't turn on

3) One bulb off & hot - corresponds to the switch you turned on first and then turned off

##### Share on other sites

Turn one light on for 5 minutes then turn it off before entering the room. Turn another switch on and enter the room. Feel the other two bulbs that are off. The one that is warm is to the first switch you turned on before you entered the room. The switch that you turned on is obvious. the switch you did not touch is the one to the only bulb left.

##### Share on other sites
This topic is now closed to further replies.