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        riddles >> microsoft >> Refrigerator Light Bulb
        
(Message started by: william wu on Mar 17th, 2003, 8:02am)
Title: Refrigerator Light Bulb
Post by william wu on Mar 17th, 2003, 8:02am
From an tech-interview ... I kid you not:

When you open your refrigerator, you can see a lit light bulb.

How would you prove that the light bulb turns off when the refrigerator door is closed?
Title: Re: Refrigerator Light Bulb
Post by towr on Mar 17th, 2003, 9:54am
go sit inside the refridgerator of course :p

use a camera/webcam
put someone else in the fridge, get the out before frozen

make it impossible for the refridgerator door to close (a very logical solution, think about it)

explain and clarify the causal path between the door opening/closing and the lightbulb being turned on/off
Title: Re: Refrigerator Light Bulb
Post by aero_guy on Mar 17th, 2003, 9:58am
I hesitated to write anything because it just looked so silly, but since someone of towr's stature semi-seriously answered I guess I can too.

Open the door to show the light is on.  Turn the temperature setting to the max (so it sin't overly cold inside).  After the lightbulb has warmed up a bit, close the frig.  Wait a couple minutes, open the frig with the now cool lightbulb.  (have to have the refrigeration setting low so you can show it just wasn't the frig cooling the bulb)
Title: Re: Refrigerator Light Bulb
Post by Icarus on Mar 17th, 2003, 5:33pm
Find the button that the door holds in when it is closed. Push the button in with your finger to see that, yes, it does indeed turn off the light. Notice that for the door to be closed, the button must be pushed in far enough to turn off the light.
Title: Re: Refrigerator Light Bulb
Post by redPEPPER on Mar 21st, 2003, 5:29am
drill a hole through the door
Title: Re: Refrigerator Light Bulb
Post by cho on Mar 21st, 2003, 7:11am
I'm sorry. None of you gets the job. Remember, you're applying for a Microsoft position. None of the given answers could be programmed into the next version of Windows. Therefore the correct answer is to invent a Windows-refrigerator, complete with wireless internet to automatically order more brie anytime you're running low. You would then check on the lightbulb status by clicking Tools/Options/Preferences/Diagnostics/Interior/Peripherals/Lightbulb/Advanced, at which point you'd see that the Lightbulb Monitor is greyed out because you must first go to the Control Panel/Light Bulb/Administrator/Permission, type in your lightbulb password (which Microsoft will invalidate after you change the lightbulb twice). Then return to Tools/Options/Preferences/Diagnostics/Interior/Peripherals/Lightbulb/Advanced/Lightbulb Monitor. You'll learn that Windows leaves the light on all the time by default. To turn it off you must locate the appropriate checkbox located somewhere in your toaster oven.
Title: :)Re: Refrigerator Light Bulb
Post by Boody on Mar 21st, 2003, 7:23am
Eternal question in fact.

in formal way:
> When you open your refrigerator, a light bulb turns on.  

should say that the light is off before turn on.    :)
But we're not sure at which moment that the light bulb turn off, is it really when we close the door ?   ???

I think that we can ask the question
- light is on or light is off when the door is closed
to the Schrödinger's cat.

:)
Title: Re:  :)Refrigerator Light Bulb
Post by william wu on Mar 21st, 2003, 11:40am

on 03/21/03 at 07:23:41, Boody wrote:
Eternal question in fact.

in formal way:
> When you open your refrigerator, a light bulb turns on.  

should say that the light is off before turn on.    :)


Nice catch; my previous phrasing presumes that the bulb is off until you open the door. I've changed the phrasing to say that you merely see an on bulb upon opening the door.
Title: Re: Refrigerator Light Bulb
Post by maryl on Mar 26th, 2003, 8:30am
What if you stuck a mirror out of the bottom of the fridge, and watched it's reflection as you open and close the door?
Title: Re: Refrigerator Light Bulb
Post by James Fingas on Mar 26th, 2003, 10:36am
With most fridges, the light bulb turns off shortly before the door is completely closed. Just close it gradually and watch the crack (especially at night). You will see the light turn off.

But I know this is too easy an answer  :(
Title: Re: Refrigerator Light Bulb
Post by BNC on Mar 27th, 2003, 3:47am

on 03/17/03 at 08:02:07, william wu wrote:
...When you open your refrigerator, you can see a lit light bulb....


My refrierator's bulb just burned out. So now, when I open my refrigerator, I do not see a lit light bulb. Hence the question is invalid  :P
Title: Re: Refrigerator Light Bulb
Post by SWF on Mar 27th, 2003, 5:13pm
BNC, if your bulb is burned out that is a good indication that a working bulb is on much of the time, and maybe it goes on when the door is shut (or you spend too much time with teh door open).  :-)

In mine the bulb is cool when the door is first opened, but heats to above room temperature in a just few seconds, so I assume it is off when shut.

Putting a running video camera inside would be practical to do and can be done with the door totally shut- no wires running out.  Could also try to grow a plant inside that thrives in low temperatures. It would quickly get ill if it is kept in the dark.

Put a phosphorescent watch inside. After a while, with a dark kitchen, unplug the refrigerator, and look at the watch.  If the phosphor is brightly glowing then the light was on inside.
Title: Re: Refrigerator Light Bulb
Post by Icarus on Mar 27th, 2003, 5:19pm
Call the "refrigerator psychic" and ask for a reading! :P
Title: Re: Refrigerator Light Bulb
Post by Mr. GuestMan on Sep 23rd, 2003, 6:43am
Of course the not so smarter, but perhaps ingenious solution would be to wire a copper wire to the socket, unplugging the lightbulb, closing the door and touching the wire to see if the wire is HOT.
Title: Re: Refrigerator Light Bulb
Post by Sir Col on Sep 23rd, 2003, 7:59am
1) Unplug the fridge, in a darkened room place photographic paper inside the fridge, and close the door. After a suitable length of time, remove the paper and examine for exposure.

2) Wire a buzzer to the light socket. Close the door. If the buzzer stops, we know the light goes off. Unless, of course, the fridge contains a rapid air evacuation device that creates an almost instantaneous vacuum when the door is closed.

3) Check the manual that came with the fridge: "Rather than run the risk of mechanical failure of the light operation switch found on most fridge doors, this refridgerator contains a unique internal illumination feature; the light is always on."  ::)
Title: Re: Refrigerator Light Bulb
Post by grimbal on Apr 30th, 2004, 3:48pm
Here is a philosophical question.  Is a light still on when there is nobody to see it?
Title: Re: Refrigerator Light Bulb
Post by grimbal on Apr 30th, 2004, 3:49pm

on 03/17/03 at 09:54:20, towr wrote:
go sit inside the refridgerator of course :p

And don't forget to take your lighter, or you won't see anything.  ;D
Title: Re: Refrigerator Light Bulb
Post by pedronunezmd on Jun 18th, 2004, 7:06am
;)

I hate to be picky, but everyone who has answered this question so far is wrong!

All of these solutions that have been proposed so far only prove that the lightbulb is off during the period of observation. For example, sitting inside the fridge and watching the bulb goes out means the bulb went out during that door closing, same with pushing the little button thingy, same with using a webcam, etc.

How do you know the rule for turning off the lightbulb isn't: when door closes, pick random number from 1 to 1 trillion, if the number = 34, then leave light on when door closes, otherwise turn light off?

The only way to prove that the lightbulb goes off when the door closes is to take the fridge apart and show the circuitry that controls "the door closing -> lightbulb turns off".

More specifically, it is actually not the closing of the door that turns the lightbulb off, what you are actually proving is that when the door closes in such a way that it pushes that little button down, then the lightbulb goes off. (If you whittled the button down to nothing, such that closing the fridge door did not result in the button being depressed, then closing the door does not cause the light to go off.)
Title: Re: Refrigerator Light Bulb
Post by Grimbal on Jun 18th, 2004, 7:28am
You are right.  It simply is not true.

There are these huge refrigerators in the food processing industry where the light is just a switch near the door.  Closing the door does not switch the light off.  Then there are the refrigerators that have no light.  Or those where the switch-off mechanism does not work.  Closing the door still does not switch the light off.

So we should reformulate the problem as: "Given a refrigerator such that there is a light inside that is switched off when the door is closed, how can you prove that the light inside is switched off when the door is closed.".  But then, it is obvious, isn't it?
Title: Re: Refrigerator Light Bulb
Post by pedronunezmd on Jun 18th, 2004, 8:12am
Well, I think the question is, "If you have one of those fancy state-of-the-art refridgerators where the lightbulb goes off when you shut the door, how would you prove to someone that that was the case, that the lightbulb did indeed go off?"

To a skeptic like me, just showing me one instance where the lightbulb went off when you shut the door would not convince me that everytime you shut the door, the lightbulb goes off. I wouldn't believe that you could afford such technology.
Title: Re: Refrigerator Light Bulb
Post by DMaJ007 on Jun 29th, 2004, 4:43pm
The answer is simple. Take out the engineer schematics of the fridge to show the wiring and effects of the door button which controls the light, then simply show that physics causes the door to latch on to the fraim via magnets or some other device. Thus when the door is open, the only way the light could indeed turn on was through the button and the only way that, using a proper non burnt out lightbulb, the bulb would be kindled would be if the button was pushed. :P
Title: Re: Refrigerator Light Bulb
Post by pedronunezmd on Jun 29th, 2004, 4:54pm

on 06/29/04 at 16:43:16, DMaJ007 wrote:
The answer is simple. Take out the engineer schematics of the fridge to show the wiring and effects of the door button which controls the light, then simply show that physics causes the door to latch on to the fraim via magnets or some other device. Thus when the door is open, the only way the light could indeed turn on was through the button and the only way that, using a proper non burnt out lightbulb, the bulb would be kindled would be if the button was pushed.
Nah, I still won't believe that the schematics were correct. You could just as easily have forged counterfit schematics or bought a forgery from a refridgerator-schematics blackmarket which are rampant in many parts of third world countries. You'll still have to show me the actual circuitry, sorry.
Title: Re: Refrigerator Light Bulb
Post by Three Hands on Jul 1st, 2004, 3:35am
Well, if you are being a true skeptic, then I couldn't successfully prove that the lightbulb exists in the first place, let alone what state the bulb is in while it is unobserved  :P

However, I think this riddle is looking more for an argument that would show beyond reasonable doubt that the bulb turns off when you shut the refridgerator door, so many of the suggestions provided so far would be fine for this (in my opinion), although some of them may wish to repeat the demonstration a few times in order to make the probability of a fluke less likely.
Title: Re: Refrigerator Light Bulb
Post by pedronunezmd on Jul 1st, 2004, 10:41am

on 07/01/04 at 03:35:21, Three Hands wrote:
However, I think this riddle is looking more for an argument that would show beyond reasonable doubt that the bulb turns off when you shut the refridgerator door, so many of the suggestions provided so far would be fine for this (in my opinion), although some of them may wish to repeat the demonstration a few times in order to make the probability of a fluke less likely.

Oh, shoot, someone is taking my posts seriously?  :-X
Title: Re: Refrigerator Light Bulb
Post by Three Hands on Jul 2nd, 2004, 4:56am
Well, I am doing Philosophy, after all. The appeal to questioning what we actually know is one which comes up quite a bit for philosophers, and the basic answer is that we know very little, but tend to believe quite a lot, and most of these beliefs (that what we see is real, that the future will resemble the past in terms of causality, etc.) appear to have caused us little harm thus far, and would probably cause us a lot of harm if actively disbelieved.

Oh, and in response to Grimbal, Bishop Berkeley's answer would be that the bulb is being constantly observed by God, and so not only continues to exist, but also remains in the state that it should  ;)
Title: Re: Refrigerator Light Bulb
Post by Grimbal on Jul 2nd, 2004, 12:21pm

on 06/29/04 at 16:54:32, pedronunezmd wrote:
Nah, I still won't believe that the schematics were correct. You could just as easily have forged counterfit schematics or bought a forgery from a refridgerator-schematics blackmarket which are rampant in many parts of third world countries. You'll still have to show me the actual circuitry, sorry.

Or simply, it could be that the carefully designed device that turns the lamp off does not work.  Isn't that what we are trying to test?
Title: Re: Refrigerator Light Bulb
Post by Saurabhdobhal on Aug 5th, 2004, 2:58am
Well I feel that first we need to prove that the light goes off when we press the button besides the door that gets pressed every time we close the door.
     Then we can add some padding behing the door so that it presses the button before the door is fully closed. If the bulb goes off then we can prove that, when the door is fully closed it would press this button and switch off the light.

But this solution works only when the lightning system is based on this switch getting pressed .. there might be newer models in the  market.... which dont follow this technique.
Title: Re: Refrigerator Light Bulb
Post by saurabhdobhal on Aug 5th, 2004, 3:09am
Hi ppl,
         got anothr idea ... eureka.
Well what we need to do is attach a very sensitive voltmeter/Ampmeter to the line supplying power to the refrigrator, now open the door and see the reading .. and then close the door and  see the reading .. if the bulb is switched off then it would consume less power. :)
Title: Re: Refrigerator Light Bulb
Post by Grimbal on Aug 5th, 2004, 2:22pm
Put your wife's favorite plant in the fridge.  A plant needs light.  If after a week or so the plant dies, it proves there was no light when the fridge was closed.  ;D
Title: Re: Refrigerator Light Bulb
Post by mattian on Aug 6th, 2004, 4:13pm
Or alternatively, it proves that the fridge is cold.
Title: Re: Refrigerator Light Bulb
Post by Aryabhatta on Aug 9th, 2004, 10:42am

on 08/06/04 at 16:13:28, mattian wrote:
Or alternatively, it proves that the fridge is cold.


Set the fridge to the highest temperature setting. This will cause the ice cubes to melt and will solve the problem of watering the plant too  ;D
Title: Re: Refrigerator Light Bulb
Post by mattian on Aug 9th, 2004, 10:49am
Or turn the fridge inside-out.
Title: Re: Refrigerator Light Bulb
Post by bishwa on Aug 16th, 2004, 3:08pm
I think it was George Bernard Shaw who said "Sufficiently adavanced technology is indistinguishable from magic.".

The light goes off by magic.
Title: Re: Refrigerator Light Bulb
Post by towr on Aug 17th, 2004, 3:51am
I think it was Arthur C Clarke..

There are some variations on the theme as well..
http://freefall.purrsia.com/ff300/fv00255.htm
Title: Re: Refrigerator Light Bulb
Post by EasyAnswer on Oct 2nd, 2004, 10:26am
OK I have a solution that'll take you seconds to see if thel light turned off when closing the door: Put you camera in the fridge, set it to take a picture after x number of seconds (no flash) and look at the picture!!!
Title: Re: Refrigerator Light Bulb
Post by Rejeev on Oct 4th, 2004, 7:42am
despite being microsoft section, there is some sense in this question! what you one can do is try to close the door as close as possible still he can peep into the fridge. He he is lucky he can see light goes off and thus prove the lemma. other wise he can't conclude anything. But proving the converse is even difficult [he want to prove that light does not goes off even after doors closes]
Title: Re: Refrigerator Light Bulb
Post by Mr Hokum on Jan 21st, 2005, 3:59am
Oh my god, in true avoid work style I just read the entire post on the fridge light on/off debate, and have come to the conclusion that despite it being logical to believe that the light does indeed go out, this may only be true to our need to believe that once we believe something it is true unless the circumstances change, but we often disregard the option that despite there being no change in causalities, the result could indeed change regardless, which would suggest that it is not possible for us to truly believe anything. So to mearly sustain the continued flow of human society the bulb does indeed go out, and disbelieving this is treason to humanity  :)
Title: Re: Refrigerator Light Bulb
Post by Icarus on Jan 21st, 2005, 8:39pm
Perhaps you should be more faithful in taking your medicine. ;) Humanity is not going to suffer greatly if you decide that events will turn out differently even though all the causes remain the same. To disbelieve all evidence and all common sense is hardly "treason against humanity". Instead, it is likely that only you and perhaps an unfortunate few around you who will be harmed by this sudden suspension of reason.

While it conceivable that the switch fails to work when pressed in by the door, though it does at other times, I think it far more likely that it will work and the light will be off.
Title: Re: Refrigerator Light Bulb
Post by Murali Mohan Saginala on Jan 26th, 2005, 3:31am
Put a wireless sensor[Hi-fi answers for questions asked by a hi-fi company :P] inside the refrigerator that detects light.
Close the door of the refrigerator and find out the results.
Title: Re: Refrigerator Light Bulb
Post by Grimbal on Jan 26th, 2005, 5:37am
Actually, there is no need to test.

No light bulb lasts forever.  If you close the door, the light bulb will extinguish ... eventually.
Title: Re: Refrigerator Light Bulb
Post by towr on Jan 26th, 2005, 6:18am

on 01/26/05 at 05:37:01, Grimbal wrote:
No light bulb lasts for ever.
Is that so? Can you prove it?
Title: Re: Refrigerator Light Bulb
Post by Grimbal on Jan 26th, 2005, 9:19am
Yes.  

::[hide]Unfortunately, the proof takes a long time.  A long long long time.  Actually, it takes an infinite amount of time.[/hide]::
Title: Re: Refrigerator Light Bulb
Post by SWF on Jan 26th, 2005, 6:32pm
There is a lightbulb in a Livermore, California firehouse that has been on for over 100 years (but not inside a refrigerator).

Looking through this thread, I noticed there are many answers being repeated as if nobody reads the previous posts- almost as bad as in the 100 Prisoners and a Lightbulb riddle. Is there something special about lightbulb questions that causes this?
Title: Re: Refrigerator Light Bulb
Post by Sir Col on Feb 20th, 2005, 4:10am
Has anyone suggested using a camera or photographic film? What about a light sensor? Maybe put someone inside the fridge, or what about a plant?  ::)
Title: Re: Refrigerator Light Bulb
Post by lizard glue on Jul 19th, 2005, 9:27pm
Just ask Ya Hoody.  He lives inside the fridge and it is his job to turn the light on and off.
Title: Re: Refrigerator Light Bulb
Post by Thomas Kim on Jul 28th, 2005, 2:10pm
In my opinion,

(1) Setup the refrigirator thermostat to room temperature.

(2) Close the door of refrigirator until the refrigirator's temperature will be same with room temperature. (Simply 1 day for sure)

(3) Open the door and touch the light burb to see
the heat. If the light burb was turned on while the door is closed, it must be hot. Otherwise it must be
similar with room temperature.
Title: Re: Refrigerator Light Bulb
Post by Shaarnga on Jul 28th, 2005, 2:57pm
Average lifetime of a bulb is say X hrs. Keep the door open for X hrs till the bulb's lifetime expires.

Now by closing the fridge if we prove that the life time of the bulb is greater than X hrs then we cna prove that its switched off when we close the door
Title: Re: Refrigerator Light Bulb
Post by BNC on Jul 28th, 2005, 5:58pm

on 07/28/05 at 14:57:04, Shaarnga wrote:
Average lifetime of a bulb is say X hrs. Keep the door open for X hrs till the bulb's lifetime expires.

Now by closing the fridge if we prove that the life time of the bulb is greater than X hrs then we cna prove that its switched off when we close the door


Statistics can be dangerous if not used carefully…
Ever heard of the statistician who drowned in a canal whose average depth was 15 cm?

Specifically, the average lifetime of bulbs gives only limited information regarding the lifetime of any single light bulb.
Title: Re: Refrigerator Light Bulb
Post by Neelesh on Sep 12th, 2005, 6:36am
We already have more than a dozen answers for this. Here are three hundred more.

http://www.godlessgeeks.com/LINKS/GodProof.htm

Just replace the phrase "God's Existance" by the phrase "Light Gets Switched off when the door gets closed."

One of the typical (Well known) arguments (From Euler) is that
(a+bn)/n = x
And hence the light indeed gets switched off.
Title: Re: Refrigerator Light Bulb
Post by wsj on Dec 17th, 2005, 1:39pm
Assuming standard home sized unit. If we replace the standard bulb by (say)100 wattage unit bulb. Then measurements of power consumption before and after  the door is closed should be the around unit consumption of the bulb.

Also If we can add an additional circuit, like XNOR gate

Door closed= True , Bulb off = True

Then
Door-Closed    Bulb-Closed  Power- ON
T                           T                       T
F                            F                       T
T                            F                       F
F                            T                       F

Power would only be supplied only when our considtions are met, and power off means no noise from the refrigerator.




Title: Re: Refrigerator Light Bulb
Post by egnorant on Feb 21st, 2006, 7:03am
I know I am new so maybe I am not into the spirit of the Microsoft thing.
My answer is to get inside the fridge and shut the door.
Bruce
Title: Re: Refrigerator Light Bulb
Post by egnorant on Feb 21st, 2006, 11:46pm
Depends upon the job I was applying for!
Since I am shooting for top exec position, I would
see to it that whoever came up with the idea was fired. Then I would steal his notes and pursue the research through quiet channels with a government grant.
After insuring that it would be a noted feature in the documentation and end users would be aware that this was an nessesary function for the proper working of many Windows applications, I would make sure the only way info was available was through our $35.00 per hour help line.
Start a university for Lite research so that bright young engineers would pay me for the privilege of working out my technical problems.
Develop "socket X" light bulbs and by contract tie up all future refrigerator manufacturers to insure that they are using
"socket X" bulbs. (X changes every 6 months!)
Flood the market with Windows compatable light bulbs(Pat Pend) made in a plant I bought in Mexico.
Improved versions would appear every 6 months and not be backward compatable.
Announce improved "Lite Tite 2.35"
for next version of Windows XS Professional version only.
Assume the title of "Father of Lite" for my Newsweek and Time articles.
Sue Linux for their knockoff "Lite emulator"
Take over Linux and buy Wal-mart.
Buy an island with no extradition policy just to be safe.
Bruce
Title: Re: Refrigerator Light Bulb
Post by Grimbal on Feb 26th, 2006, 1:49pm
And when hiring young engineers, ask them how they would test a computer operating system.
Title: Re: Refrigerator Light Bulb
Post by egnorant on Feb 26th, 2006, 8:27pm
You could install "windows"  ;D in the refrigerator!
Bruce
Title: Re: Refrigerator Light Bulb
Post by Grimbal on Feb 27th, 2006, 3:30am
Or install a penguin.  ;)
Title: Re: Refrigerator Light Bulb
Post by NumBeast on May 12th, 2006, 1:16pm

on 03/17/03 at 09:58:45, aero_guy wrote:
Open the door to show the light is on.  Turn the temperature setting to the max (so it sin't overly cold inside).  After the lightbulb has warmed up a bit, close the frig.  Wait a couple minutes, open the frig with the now cool lightbulb.  (have to have the refrigeration setting low so you can show it just wasn't the frig cooling the bulb)

this is the only reasonable answer so far
Title: Re: Refrigerator Light Bulb
Post by spikegomez on Nov 26th, 2008, 8:25am

on 03/17/03 at 08:02:07, william wu wrote:
From an tech-interview ... I kid you not:

When you open your refrigerator, you can see a lit light bulb.

How would you prove that the light bulb turns off when the refrigerator door is closed?


You may put you laptop inside your refrigerator and enable the camera and make sure that the camera is on front of the light bulb...
-----------------------------
// de-spammed
Title: Re: Refrigerator Light Bulb
Post by k2xl on Feb 16th, 2009, 2:33pm

on 07/28/05 at 14:10:15, Thomas Kim wrote:
In my opinion,

(1) Setup the refrigirator thermostat to room temperature.

(2) Close the door of refrigirator until the refrigirator's temperature will be same with room temperature. (Simply 1 day for sure)

(3) Open the door and touch the light burb to see
the heat. If the light burb was turned on while the door is closed, it must be hot. Otherwise it must be
similar with room temperature.



I agree with this.
Title: Re: Refrigerator Light Bulb
Post by iono on Feb 23rd, 2009, 6:54pm
change to a new lightbulb that burns out after being on for a fixed number of hours. Leave the fridge door closed for a long enough time so that if the bulb was on all the time, it would burn out. Open the door to see if light still works.

You can also check your electric bill or something.
Title: Re: Refrigerator Light Bulb
Post by chronodekar on Jun 24th, 2009, 2:52am
The question asks us to PROVE that the light-bulb turns off when the door is closed.

The answer I liked is to just push the button on the refrigerator door to check if the light goes off.

My contribution,
[hide]Replace the bulb with a buzzer. You should hear noise when you open the fridge and silence when you close the fridge. (And PLEASE, don't go about saying that the fridge door is sound-proof...)[/hide]

I think that will prove beyond doubt if the light goes off when the door is closed.

-chronodekar


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