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Below you will see how my "understandings" and obsevations are in conflict. Please look them over and let me know what I am missing.

  1. Absorption: Light can only be absorbed by an atom if it has the exact eV to match the atom's "required" eV. When this happens the electron jumps to a higher state, but falls back down and in the process emits a photon or photons that equal the eV that was absorbed. I think I understand this.

  2. The Observation: If I shine a red light in a dark room I can see basically everything, but the red light produces an eV of say 1.9074eV. It's very unlikely that all of the objects in the room have an obsorption "requirement" of exactly 1.9074eV. How is the light being reflected? I don't think bounced is the right answer. What am I missing??

  3. The Observation: If I shine polarized light onto a polarizing filter. The polarizer will reduce the light as I rotate the filter, but it will do it with light of all sorts of eV, red, green, blue, etc. If the energy is lost by heat, wouldn't that require infared waves to be emitted?

I have looked for questions already posted on the topic, but was not satisfied. I think the answer may be that I need to consider the molecule not just the atom.

Thanks

Lambda
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  • " I need to consider the molecule not just the atom." And the lattice, which is a quantum mechanical bound state of a ensemble of atoms. my answer here https://physics.stackexchange.com/questions/633278/what-exactly-happens-during-the-reflection-of-light-at-the-atomic-level/633308#633308 and here https://physics.stackexchange.com/questions/80919/what-causes-atoms-to-have-their-specific-colors/80922#80922 may help – anna v Mar 16 '23 at 04:42
  • In physics so much has been learned by studying light with pure atoms (many in a gas state) .... QM was originally based on hydrogen study for example. But we can take pure silicon and make a large solid where QM says we have a semiconductor and we get an energy band ... i.e. a broad absorption band. – PhysicsDave Mar 16 '23 at 12:43
  • In a room almost all objects are molecules ... they also have a broad band of absorption .... and they also have a broad band of emission is the IR. – PhysicsDave Mar 16 '23 at 12:45

1 Answers1

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(1) Photons can be absorbed without re-emitting light. The photons energy is absorbed and heats up the matter. As it get hotter the atoms bump into each other and radiate infrared heat. Think of black surfaces. (2) If the walls of the room reflect any light at all, it's because the walls are not absolute black. And the small amount of light reflecting is red because that the only light being used. (3) Polarizers do absorb photons and the energy is radiated as Infrared heat.

Bill Alsept
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