Why I can burn a paper with magnifying glass and sun?

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Burning paper with a magnifying glass and sunlight occurs due to the concentration of light energy into a small focal point, which raises the temperature of the paper above its combustion threshold. Light is an electromagnetic wave that carries energy, and when focused by the lens, it increases the energy density at that point, causing the paper to heat rapidly. The process involves exciting electrons in the paper, leading to a chemical reaction with oxygen that releases energy in the form of heat and light, known as combustion. The magnifying glass also serves to bend light rays, allowing for magnification of images by refracting the diverging rays into a converging path. Understanding these principles clarifies both the burning process and the magnification effect of the lens.
  • #31
Sorry to interrupt you here, but if the chemical reaction of combustion is occurring only at the paper, then why is light coming from the entire flame, which may be several cm long?

It follows it's not just the paper that's burning, also gases emitted from it when heated are burning. What gases would paper emit when heated?
 
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  • #32
Ulysees said:
Sorry to interrupt you here, but if the chemical reaction of combustion is occurring only at the paper, then why is light coming from the entire flame, which may be several cm long?
That's what burning is. This is a different discussion.
 
  • #33
Ulysees said:
Sorry to interrupt you here, but if the chemical reaction of combustion is occurring only at the paper, then why is light coming from the entire flame, which may be several cm long?

It follows it's not just the paper that's burning, also gases emitted from it when heated are burning. What gases would paper emit when heated?

light doesn't *come* from the flame. The appearance of light from somewhere makes you assume that there is a flame there. And yes.. as dave suggested this is a totally different discussion. We are mixing optics, thermodynamics and atomic structure all at the same time which a good combination makes not :D
 
  • #34
And how I can determine, how big I'll see the http://laser.physics.sunysb.edu/~jennifer/pictures/refraction.gif" Why X is like on the picture?
 
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  • #35
> light doesn't *come* from the flame.
> The appearance of light from somewhere makes you assume that there is a flame there

And what is the deep philosophical difference between these two? :-p Of course there is light coming from the flame! Of course there is a flame 2 centimetres from the paper! It's gas. Anyway, this is too philosophical for me :-p. See you guys.
 
  • #36
is a magnifying glass and the sun a form of clear heat?
 
  • #37
rena g said:
is a magnifying glass and the sun a form of clear heat?

This thread is 3 years old. You should start a new thread to ask your question.

In asking your question, you should describe what you mean by "clear heat", since there is no such scientific term.
 

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