How is a spark created from scraping metal to start a fire?

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In summary, sparks are created when metal is scraped against another metal, either by accident or on purpose.
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On a fundamental level, can anyone explain how a spark is created from scraping a knife along a piece of metal as done by people who want to light fires 'in the wild'?
 
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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.
 
  • #3
LostConjugate said:
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".
 
  • #4
Drakkith said:
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.
 
  • #5
Thank you.
 
  • #6
Then how can it be a spark?
 
  • #7
"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.
 

1. What is a spark?

A spark is a small, visible electrical discharge that occurs when there is a high voltage difference between two conductors.

2. How is a spark created?

A spark is created when an electrical current jumps through the air or another gas, ionizing the particles in its path and creating a visible plasma discharge.

3. What causes a spark to occur?

A spark is caused by the buildup of an electrical charge, which can occur through friction, heat, or a high voltage source.

4. Can a spark be created without electricity?

No, a spark can only be created through the flow of electricity. However, other forms of energy, such as heat or friction, can generate the initial electrical charge needed for a spark to occur.

5. What are some practical applications of sparks?

Sparks have a variety of practical uses, such as in spark plugs for igniting fuel in internal combustion engines, in welding processes to melt and join metal, and in lighters and matches for starting fires. They are also used in entertainment, such as in fireworks and Tesla coils.

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