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More ways to get Braingle...

The Right Switch

Logic puzzles require you to think. You will have to be logical in your reasoning.

 

Puzzle ID:#363
Fun:*** (2.97)
Difficulty:** (2.08)
Category:Logic
Submitted By:Noctus*
Corrected By:Dave

 

 

 



In front of you are three light switches. Only one does anything, and it turns on the light downstairs. From here you can't see the light, and it makes no sound. You must determine which switch operates the light, BUT you can only go check it once. How do you figure out which switch is for the light?



Answer

Flip any switch you want. Wait for about 5-10 minutes to let the bulb heat up. Flip that same switch off, and another one on. Go check the light. If it's off and hot, it was the first switch, if it's on it was the second and if it's cold and off, it was the last one.
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Comments

Adamko**
Oct 08, 2002

Love this puzzle. Didn't take too long to answer but still great
Rowsdower*
Dec 24, 2003

Clever!
boodlerAgb*
Nov 25, 2005

'fraid I'd no idea! excellent!
stephiesd**
Dec 15, 2005

wow. i was off.
choptlivvaAus*
Dec 16, 2005

Cool!!! (pun intended)
musicmaker21113
Jan 19, 2006

But... what if it's a fluorescent light bulb?

Just kidding... great teaser!
magicumbreon*
Feb 06, 2006

That is really sneaky!
jntrcs*
Mar 27, 2006

I didnt know that was a possibiblity
Vigo95Aus*
Mar 28, 2006

i liked this alot !!!
warmonkey318Aus*
Mar 29, 2006

wow..i didnt get that one, it was really good!
Mellew*us*
Mar 30, 2006

this wasnt my first time doing this one but on my first time i actuaky got it rite
TehIgnored*us*
Apr 02, 2006

That's an electricians riddle my cousin told me....it took me about 10 minutes to get it when he told...but I finally did.....

I'd heard it before, but I based the difficulty on that....not that I knew the answer....

WONDERFUL TEASER...i love this one
elshawnoAus*
May 09, 2006

loved it... although I heard it a long time ago, I forgot...
McGee*us*
May 09, 2006

classic, already knew it in about 5 other styles.
Zealot
Aug 01, 2006

awww, i had no idea. 'twas a good one
scallioAus*
Aug 01, 2006

Awesome teaser! Didn't get the answer, but it is a great teaser!
OldChinaHand**
Aug 01, 2006

Simple, flip a switch, send the wife down to check, flip another switch, send the wife down again until you find the right one; then you go down once to make sure, you know how wives are. Then you take your hammer and smash the other two extra switches to pieces...right? But really, this was a fun teaser to solve.
marschie*il*
Aug 01, 2006

Very, very clever ...but what if it's an office building with a high ceiling?? All the "what-ifs" in the world won't change the cleverness of this teaser. Good job!
bluehawk*us*
Aug 01, 2006

OOOOOOKKKKKAAAAAYYYYY!!!!!
Not real logical to me, but ,,,,,,,,,,,
OOOOOKKKKKAAAAAYYYYY!!!!!!!!!
utnative*
Aug 01, 2006

i'm not a logical thinker i guess. i wasn't even close. good teaser, poor solver
curious_george*us*
Aug 01, 2006

Darn... I was going to submit this exact riddle once I got enough points... Oh well
(user deleted)
Aug 01, 2006

There is a slight problem here: it says you can check it only once and I suppose that covers both the cases whether you check it for its glow or its temperature. Therefore logically the solution is not valid.

Of course if you want to relax the conditions a little, you have to say you check it for its glow.

But mathematically, you have to check twice, which is what is done in the solution anyway.

Good puzzle!
(user deleted)
Aug 01, 2006

The definition of "check" can easily include two (or more) aspects something's status. In fact, the word is more commonly used to encompass multiple items. The riddle did not say "check to see if the light's on," and is therefore 100% consistent.

Most bulbs heat up quickly and it would take some experience to make an assessment of the switch based on the temperature.
pating**
Aug 01, 2006

i like this teaser, even though i heard it before. you just know there's got to be a twist somewhere.
underherfeetca
Aug 01, 2006

To all, you are only checking once, flip first switch on then off, then flip second, then go down, warm, was first, on, is second, off, it's third, if none work, wrong set of switches?
bradon182001*us*
Aug 01, 2006

Interesting. I sure didn't come up with the right answer.
jkramer470
Aug 01, 2006

You could always turn them all on and just not care witch one it is.
coachpisco*
Aug 01, 2006

I thought you could only flip the switches once. So if I checked and the light was on, fine. If not, I went back and flipped the last switch. I guess I mis-read the instructions.
cyberstar5150*us*
Aug 01, 2006

Flip 'em all. Teaser solved.
kcheer2493us*
Aug 01, 2006

That didn't even cross my mind!
Very Creative. Thanks
Badger*us*
Aug 01, 2006

I think the logic is clever and flawless... Didn't get the answer, though! I had the wife & kids downstairs with walkie talkies... Had the switch dismantled with a volt/ohm meter at the ready(lol). I like the logic & situation probs. Broke my daily streak on this one. Good job! Too bad it sounds like an oldie. Thanks!
monkeygrl99Aus*
Aug 01, 2006

I think that this one was really hard, because I wasn't even thinking about tthe answer!
FeaerFactorY666*us*
Aug 01, 2006

ahah!! verry nice!!!
enjaytee
Aug 01, 2006

What does it matter if two of the switches don't work. Just turn them all on. It was a good teaser tho
Neek*us*
Aug 01, 2006

Great logic puzzle. Of course, I didn't get it. I'm pretty sure I haven't solved any of the logic puzzles at all. I'll keep trying.
Pizzazz2uAus*
Aug 01, 2006

Very cleverly thought out teaser! I did know the answer beforehand, which made it easy for me to know the outcome. But, to other individuals, it does make them think. Keep them coming! I have had some clever teachers during my years, including young kids and older kids.
iteachkidsAus*
Aug 01, 2006

OldChinaHand, you are a STITCH!
My only question is this - what if I can't reach the bulbs to touch them???? Hope there's a ladder in there!
speedqueenkmwAus*
Aug 01, 2006

I'd just wait for a helper downstairs.
heyman*
Aug 01, 2006

I agree with BeeneB. Because of the wording one would not have been able to give the same answer as the writer. I came to a different conclusion.

My conclusion was based not on using the light to go downstairs but to know which switch turned the light on. My analysis is: Turn on any light. Go down stairs. If it is on then there you have it. If it is not, then turn on another, then go downstairs not for checking but to use the light. If it is off, then you know the last one was the right one!
unConfuseMegb*
Aug 01, 2006

i didn't care for this one...
wizkid**
Aug 01, 2006

I've solved this one before but a different way.
shawneeo*us*
Aug 01, 2006

I thought this was great! I never heard it before, and I didn't get it, but its perfect as far as I'm concerned.

some of you, I don't think you have any idea what you're talking about! I mean... REALLLLLLY!

Thanks aa lot, loved it, good-o!

kwelchansAus*
Aug 01, 2006

How do we know that the light is off to begin with?
c_rae*us*
Aug 01, 2006

Unfortunately I didn't get it. I really had to read the answer closely and reread the puzzle in order to understand it.



I guess I need more coffee!! Good teaser!
kman613**
Aug 01, 2006

Excellent puzzle. It stumped me!
doka13*ml*
Aug 01, 2006

interesting
AZTTT**
Aug 01, 2006

Nicely done! I had considered putting a glow-in-the-dark sticker nearby, then doing the same thing with the first two switches. Your hint cued me in on the heat thing. Great job!! keep em coming!

ItsJustWildman*us*
Aug 01, 2006

Grew impatient and cheated. But good teaser!
FulanitoGM*sv*
Aug 01, 2006

It took 27 comments for someone to finally say the totally obvious answer: "turn them all on." If the other two don't do anything, like the teaser says, what does it matter if they're switched on? I think the solution makes life harder than it already is! I'm just sayin'...
somnambulist*us
Aug 01, 2006

This was a good one!
labsmith*um*
Aug 01, 2006

That was a great teaser. I thought of checking the voltage meter, wondered if the switch could get warm, didn't think it was possible any other way. Darn,I didn't get it.
HScott13Aen*
Aug 01, 2006

Clever! Didn't think of that.
syracuse945*ph*
Aug 01, 2006

veryyy clevr... th@ idea nvr crossd my mind, of course... haha... it took me a cuple of reads 2 get the solution, but aftr, i was, lyk, "o my gosh, th@ makes sense! now i feel s2pid"...

good job!
temishoau*
Aug 01, 2006

i have a friend who always tell riddles like this one! so i've heard it before, but its cool.
jabdrAus*
Aug 01, 2006

I thought I was sooo clever. I picked the 'right' switch (not the left one or center on) because logic told me the Answer was in the title. The RIGHT switch. Yes, I feel pretty dumb now!!
jcann*us*
Aug 01, 2006

How can "Turn them all on" be right? The question doesn't say that your job is to turn on the light, but to determine which switch controls the light. If you flip them all, of course the light will be on, but you still will not know which switch did it!
thimblenogginus*
Aug 01, 2006


If I could only switch on the light bulb over my head!
Musikman212*ca*
Aug 01, 2006

That was kinda different. I liked it though.
(user deleted)
Aug 02, 2006

The idea is to determine which switch works not to limit you to only one switch. Throw two switches then check if the light is on.If not the one left is the right one.If on throw one of the two switches off and you will know which switch is the right one.
naeem_ng**
Aug 02, 2006

Oooh, good one!
RRAMMOHAN*in*
Aug 04, 2006

Couldnt get the answer despite two days of sporadic thinking. Good teaser based on common knowledge. Made us all think:some with success, some without!
ragdol13
Aug 07, 2006

wow i have no idea wtf that teaser meant...but cool..? i guess
ragdol13
Aug 07, 2006

y not just turn them all on at the same time yo?
lmurray*cn*
Aug 08, 2006

XIEXIE NI! THANK YOU! HEN HAO!

VERY GOOD. I APPRECIATE THIS ONE, I REQUIRED A LITTLE THOUGHT.

PLEASE KEEP THEM COMING.
vlermaAus*
Aug 08, 2006

Heavenly days, Imurray the light does shine for you. Great teaser, that I hadn't heard before so let's just say "I Saw the Light."
expertcoder*
Aug 12, 2006

That was funny.
luvdoritos706*ph*
Sep 05, 2006

that is very smart....i probably would have never gotten that if i had to do that
QrystalAca*
Sep 18, 2006

Ooo, I forgot I fave'd this one awhile back, and now I'm here to say how awesome I think this teaser is.

Upon reading the comments, I have to agree that kwelchans has a good question. There is no way for us to know that the light was off to begin with, and the whole situation is thrown off if the light was on. (Then we'd HAVE to put up an uncharged glow-in-the-dark sticker in the room before heading up to the lightswitches...)

I think we have to say that the light was off to begin with.
ciotogca*
Nov 18, 2006

Besides to make this a teaser, why can you only check once? Surely if you can only check once, you don't have the luxury of time as suggested in the answer.

Perhaps I just expect too much, but I can't help thinking that the world would be a better place if everyone had higher expectations.
Jimbo*au*
Mar 11, 2007

I'm glad I don't have to live wih some of these whinging pedants. I thought it was an excellent logic teaser. Simple explanation and clever.
jin10doh
May 17, 2007

One of the best teasers I've ever done! Very creative!
Kudos!
princessptAus*
Sep 28, 2007

sweet! very very creative teaser!
biztycl
Dec 25, 2007

The 3 switches is already written by someone else too. One more solution, turn first one on, second one off, and the third one flick it 1 million time (since there is no restriction on how many times you could flick it) and the 3rd bulb will guarantee to blow because it has limited life span to be turn on X number of times and there you have your 2nd solution - 1st on, 2nd off, 3rd BLOWN.



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