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How is a spark created?

by InsertName
Tags: fire, metal, spark
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InsertName
#1
Jun21-11, 02:26 PM
P: 27
On a fundamental level, can anyone explain how a spark is created from scraping a knife along a peice of metal as done by people who want to light fires 'in the wild'?
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LostConjugate
#2
Jun21-11, 04:08 PM
P: 842
Electrons are removed from the metal causing it to become charged, then a spark may occur even at such a low voltage because of the very small surface area at the edge of a knife.
Drakkith
#3
Jun21-11, 05:01 PM
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Quote Quote by LostConjugate View Post
Electrons are removed from the metal causing it to become charged, then a spark may occur even at such a low voltage because of the very small surface area at the edge of a knife.
I'm not sure this is correct. From wikipedia on Flint: When struck against steel, a flint edge will produce sparks. The hard flint edge shaves off a particle of the steel that, heated by the friction, reacts with oxygen from the atmosphere and can ignite the proper tinder.

I think a similar effect is happening between a knife and metal. It generates high friction which produces "sparks".

DragonPetter
#4
Jun21-11, 06:09 PM
P: 834
How is a spark created?

Quote Quote by Drakkith View Post
I'm not sure this is correct. From wikipedia on Flint: When struck against steel, a flint edge will produce sparks. The hard flint edge shaves off a particle of the steel that, heated by the friction, reacts with oxygen from the atmosphere and can ignite the proper tinder.

I think a similar effect is happening between a knife and metal. It generates high friction which produces "sparks".
Yes, I think sparks are actually pieces of the metal heated by friction, and the temperature causes the metal embers to be incandescent.

I don't think it is an electrostatics phenomenon.
InsertName
#5
Jun22-11, 06:54 AM
P: 27
Thank you.
LostConjugate
#6
Jun22-11, 11:10 AM
P: 842
Then how can it be a spark?
nasu
#7
Jun22-11, 12:53 PM
P: 1,969
"Spark" has (at least) two meanings.
One is a small incandescent particle.
If talking about a fire, "spark" means small incandescent particle (of carbon, usually).
The second meaning of "spark" refers to an electrical discharge.


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