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Topic: 4 light bulbs (Read 714 times) |
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alien2
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4 light bulbs
« on: Aug 11th, 2007, 7:03am » |
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This riddle is a similar version of the 3 light bulbs riddle, and everything is the same, except for the fact that there are 4 light bulbs and 4 switches. Have fun!
Just in case someone isn't familiar with the riddle, here is the link of a recent one.
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| « Last Edit: Aug 11th, 2007, 9:35am by alien2 » |
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denis
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Re: 4 light bulbs
« Reply #1 on: Aug 11th, 2007, 10:03am » |
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I assume all switches are off to begin with.
Label the switches A,B,C,D. Turn on switch A and B. Wait ten minutes, then turn off switch B and turn on switch D. Go immediately in the room:
The bulb that is on and hot is A
The bulb that is on but just starting to warm up is D
The bulb that is off and cool is C
The bulb that is off but still hot is B
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| « Last Edit: Aug 11th, 2007, 10:05am by denis » |
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Grimbal
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Re: 4 light bulbs
« Reply #2 on: Aug 11th, 2007, 2:44pm » |
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Switch them all on for 10 minutes.
Turn off A, B, C, D in turn, waiting a minute between each.
Go to the room and make a precise measurement of the temperature. From coldest to hottest, you get A, B, C, D.
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alien2
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Re: 4 light bulbs
« Reply #3 on: Aug 15th, 2007, 7:30am » |
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on Aug 11th, 2007, 10:03am, denis wrote:I
The bulb that is on but just starting to warm up is D |
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Yep, that could work, but then you have to rush in the room like the wind. I propose a bit different approach. So, at a particular moment, you turn on one switch, wait for 20-30 seconds or so, and then turn it off. Like this, a narrower part of the glass bulb heats a bit more quicker, and it cools down significantly more slower, as the bigger part of the glass bulb is not that warm. The difference is obvious, or at least, it was with two different bulbs I have tested that way.  
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Grimbal
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Re: 4 light bulbs
« Reply #4 on: Aug 15th, 2007, 7:33am » |
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If the room is very large, so large in fact that the light of the light bulbs needs minutes to reach the door, I can think of another solution. 
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alien2
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Re: 4 light bulbs
« Reply #5 on: Aug 15th, 2007, 7:51am » |
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Perhaps this riddle isn't over. 
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Death
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Re: 4 light bulbs
« Reply #6 on: Aug 16th, 2007, 4:34pm » |
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Grimbal, would this consist of you turning each of the switches on and off again, walking into the room and the first lightbulb you see turning on is the first switch, the secong bulb is the second switch, etc.
Of course the problem is then that the lightbulbs would be too far away to distinguish but that can be overcome by having them in 4 corners of the room and the door that you go through as a trap door.
I realise that this is massively complicated but at least it's something. 
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The theory goes that a million monkeys typing at a million typewriter will produce the entire works of Shakespeare. Now, thanks to the internet, we know that's not true.
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alien2
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Re: 4 light bulbs
« Reply #7 on: Aug 16th, 2007, 4:39pm » |
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Death, you are killing me.  
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Death
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For every sprinkle I find, I shall kill you
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Re: 4 light bulbs
« Reply #8 on: Aug 16th, 2007, 4:59pm » |
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I try my best
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The theory goes that a million monkeys typing at a million typewriter will produce the entire works of Shakespeare. Now, thanks to the internet, we know that's not true.
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