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How is a spark created?

  1. Jun 21, 2011 #1
    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'?
  2. jcsd
  3. Jun 21, 2011 #2
    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.
  4. Jun 21, 2011 #3


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    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".
  5. Jun 21, 2011 #4
    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.
  6. Jun 22, 2011 #5
    Thank you.
  7. Jun 22, 2011 #6
    Then how can it be a spark?
  8. Jun 22, 2011 #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.
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