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Understanding Energy Transferring

  1. Aug 9, 2010 #1
    I do a lot of random thinking - and to disclaim myself, I have no formal education on any physics. Everything I know is self-taught, so bare with me. The question I might ask my very well be worded wrong and sound stupid.

    My main question is: From what I understand - the sun(and other stars) emit a specific range of energy from the electromagnetic spectrum. Does a single photon contain all of that energy, or just a specific wavelength of that energy and its the packet that contains the full range? And does all(most) energy from the sun travel via photons?

    I understand that solar flares would contain energy and that would be another form of transferring energy - but I just want to see if I understand photons and energy transferring correctly.

    Ok, lets say I set a ice cube on the ground out in the sun. Ignoring the thermal energy coming from the ground - from what I understand - the photons with their energy travel and hit the ice cube. The electrons in the atoms on the surface of the ice cube absorb this energy where when high enough the electron cloud jumps up one level, and as energy is being released the electron cloud drops back down causing another photo to be emitted - probably a poor explanation of the photoelectric effect - but I'm doing my best.

    So, then some of the energy that is absorbed causes the molecules to loosen their bonds causing the ice to melt into water, and the the water into steam. Heat is felt on the steam because of the excess energy it contains - the energy is transferred from the steam to the air around it by the interacting electrons, and then from the air to your hand.

    Ok so basically depending on the color of an object will determine the amount of energy absorbed and the amount of energy ejected/rejected/reflected.

    Which brings me to my next question. Is all "rejected" energy light? I'd imagine I could answer that question my self because of hearing echoes and sounds from the living room as I type this... I assume if "radio" energy is emitted from the sun, as I assume it does, it would behave similarly - which is why microwaves heat food containing water... the water absorbs the energy which producing heat....

    Now, why is it that photo energy is released or "rejected" instantaneously but absorbed energy is released over time?

    I guess the release of absorbed energy is dependant on the environment around it????

    So like in a vacuum the energy absorbed would remain absorbed and never release its energy - I'm assuming that if the absorption become saturated it will it release energy?? Kind like a light bulb on how the filament glows and heat is released. Outside the vacuum the filament would release its energy in the presents of oxygen which would cause it to rapidly heat up and burn.... I get that much.... hmmm

    Geez I ask to many questions I know. I'm just trying to see if I understand this all.

    I don't know if this post has direction or can be discussed in any way... but please give me some insight and corrections. Thanks!
  2. jcsd
  3. Aug 9, 2010 #2

    Andy Resnick

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    I'm having a hard time understanding what you are really asking about- are you asking if light possesses energy?
  4. Aug 9, 2010 #3
    I'll try to bear with you :P

    Each photon (in any situation) has a particular frequency and a particular energy (see: http://en.wikipedia.org/wiki/Photon); the range of frequencies (wavelengths) and the intensity of the total energy emitted is created by emitting LARGE numbers of photons (very roughly, something like 10^50 photons/second). A "packet" isn't a clear thing, its often used to refer to a single photon.
    Very nearly-all of the sun's energy comes through photons, yes (the solar wind carries some too).

    When an electron absorbs the energy of a photon to move to a higher energy level, thats called "line absorption," and has little to do with the melting of the ice. The ice melts because (as you say) the molecules are excited thermally (they get hit by a photon, and start moving faster), weakening the intermolecular forces (not bonds) which hold the molecules in the crystal structure of ice.

    "Rejection" is not a physical property, I don't know what you're talking about--sorry. Try reading this: http://en.wikipedia.org/wiki/Planck_constant#Black-body_radiation

    You might enjoy grabbing a physics textbook and working through it.
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