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Author Topic: Why can a candle be blown out?  (Read 13134 times)

MichaelMattioni

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Why can a candle be blown out?
« on: 11/09/2008 10:37:13 »
Michael asked the Naked Scientists:
Dear Chris and other Nakeds,

Why is it that the flame of a candle can be blown out? You can make a
fire grow by blowing on it and feeding it oxygen. Why doesn't blowing hard on a candle flame make it grow bigger? Thanks!

-Michael
Virginia, USA

What do you think?
« Last Edit: 14/10/2008 12:58:06 by BenV »


 

Offline Karen W.

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Re: Why can a candle be blown out?
« Reply #1 on: 11/09/2008 14:57:49 »
Maybe it needs more fuel, someplace for it to go! It can't travel further then the length of the wick....Just a uneducated guess though!
« Last Edit: 11/09/2008 20:52:48 by Karen W. »
 

Offline lightarrow

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Re: Why can a candle be blown out?
« Reply #2 on: 11/09/2008 18:32:21 »
 

Offline rosalind dna

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Re: Why can a candle be blown out?
« Reply #3 on: 11/09/2008 23:06:40 »
It is most likely becauses the oxygen has been extinguished from the candle
 

Offline lightarrow

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Re: Why can a candle be blown out?
« Reply #4 on: 13/09/2008 11:21:12 »
It is most likely becauses the oxygen has been extinguished from the candle
What do you mean exactly? If you blow at it you send air and so oxygen.
 

Offline Bored chemist

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Re: Why can a candle be blown out?
« Reply #5 on: 14/09/2008 10:36:40 »
I think the simple answer is that when you blow out the flame you add a lot of cool air to it, once it's too cold the flame goes out.
 

lyner

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Re: Why can a candle be blown out?
« Reply #6 on: 16/09/2008 15:22:39 »
Remember the 'fire triangle'?  You need all three to sustain a fire.
 
            heat


 fuel               oxygen

Blow hard enough and you remove heat faster than the flame can supply it. Blow hard enough and you can even blow out a bonfire.
 

Offline ukmicky

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Re: Why can a candle be blown out?
« Reply #7 on: 01/10/2008 22:28:16 »
Remember the 'fire triangle'?  You need all three to sustain a fire.
 
            heat


 fuel               oxygen

Blow hard enough and you remove heat faster than the flame can supply it. Blow hard enough and you can even blow out a bonfire.
If i was in the coldest place on earth on the coldest day ever recorded with out any wind would that mean a match would burn slower or maybe not at all. :)
« Last Edit: 01/10/2008 22:36:06 by ukmicky »
 

lyner

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Re: Why can a candle be blown out?
« Reply #8 on: 06/10/2008 23:31:23 »
I guess it may burn slightly slower because the unburnt bits would be a bit cooler and take a bit longer to get warm enough to combust.
 

Offline backgroundwhitenoise

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Re: Why can a candle be blown out?
« Reply #9 on: 13/10/2008 23:36:49 »
Remember the 'fire triangle'?  You need all three to sustain a fire.
 
            heat


 fuel               oxygen


Remove the oxygen from a fire and it will be extinguished, we breathe out carbon dioxide, CO2 is not oxygen and it will kill a flame,its just like what happens when you cover a flame with a box or upside down glass or something, when the flame has only carbon dioxide surrounding it, it goes out
 

lyner

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Re: Why can a candle be blown out?
« Reply #10 on: 14/10/2008 12:53:07 »
Your exhaled air has plenty of Oxygen left in it, though. The kiss of life relies on this.
 

Offline kaypep

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Why can a candle be blown out?
« Reply #11 on: 18/10/2008 14:16:11 »
Your exhaled air has plenty of Oxygen left in it, though. The kiss of life relies on this.

not as much, right? thats why if you partially cover a flame with the base exposed it'll still go out.

it lowers the pressure at the flame, creates a partial vacuum without air/oxygen, and the flame momentarily goes out.

PS: CO2 doesn't kill fire, it just removes O2 which kills the fire. any inflammable gas can kill the fire if you put it that way.
 

Offline DoctorBeaver

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Why can a candle be blown out?
« Reply #12 on: 23/10/2008 17:32:52 »
Your exhaled air has plenty of Oxygen left in it, though. The kiss of life relies on this.

not as much, right? thats why if you partially cover a flame with the base exposed it'll still go out.

it lowers the pressure at the flame, creates a partial vacuum without air/oxygen, and the flame momentarily goes out.

PS: CO2 doesn't kill fire, it just removes O2 which kills the fire. any inflammable gas can kill the fire if you put it that way.

"any inflammable gas can kill the fire if you put it that way."

Are you sure? Did you mean "non-flammable"?
 

Offline Bored chemist

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Why can a candle be blown out?
« Reply #13 on: 23/10/2008 19:25:17 »
Good current practice in the field of things like saefty engineering deprecates the term inflamable because it causes so much trouble in translation.
Inflammable means the same as flammable; incombustible is the oppostie of combustible.
Don't you love the English language?
 

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Why can a candle be blown out?
« Reply #13 on: 23/10/2008 19:25:17 »

 

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