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Simple (?) question regarding reflection of light

  1. Nov 14, 2014 #1
    Does natural light when it hits an object cause transition of electrons between energy states and depending on the chemical composition of the material (hence the size of the transition) determine which colour we see?

    So everything around us is emitting light (photons)? Everything around us is being excited by light and emitting its own intrinsic light?

    I understand there is a reflection of certain wavelengths of light that depends on the absorption and reflective properties of the material, but I'm trying to understand this from a quantum point of view.

    Thanks for any ideas.
  2. jcsd
  3. Nov 14, 2014 #2


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    Not always. Electronic transitions are only one means for large molecules (which is what most non-metallic materials are made of) to absorb light. There are other methods too, including different types of vibration states along with translational and rotational motion. These may or may not have quantized energy levels. If not, they can absorb a wide range of wavelengths instead of a single wavelength.

    No, reflection is not a "emission" of light. The light is being reflected, so none of the energy of the reflected light is ever transferred to the reflecting medium. To emit light requires that the medium give off energy that it previously absorbed. A specific case of an object absorbing light and the re-emitting it is florescence, where specific electronic transitions in the material emit light after they have been excited.
  4. Nov 14, 2014 #3
    thats a very clear explanation, many thanks!
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