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This may be a really simple question: If electrons only absorb specific wavelengths of light and then emit them and that’s how we see color, but what happens to the other wavelengths?

Without them being absorbed they would just pass through in my mind, but no light does get through a sufficiently thick material.

It does not really make sense to me what happens with the other wavelength and I hope someone can clear that up for me. Thanks.

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It is assumed that the spectrum of electromagnetic radiation - and light is beside infrared, ultraviolet, X-rays or gamma radiation only a little part of is radiation - is continuous. Continuous means, that one can measure photons on all frequencies.

If electrons only absorb specific wavelengths of light and then emit them and that how we see color, but what happens to the other wavelengths?

Your confusion comes from replacing the fact how the identification of a chemical element through its absorption or emission spectrum takes place. Not the absolute frequencies of the excited states of the electrons is of interest, but only the relative distances to each other. This is obvious if some remember that the gas or solid during the measurement would have different temperatures. Sodium on the sun would be hotter than sodium on earth. You could identify this element only, if you compare the relative distance of the frequencies from this element.

Without them being absorbed ... but no light does get through a sufficiently thick material.

After absorption a re-emission happens. This can be as a reflection or - on very low frequencies (infrared) into the deep of the wall. (Read also about phonons, if you are interested.)

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  • $\begingroup$ I think my confusion about absorption may be due to there seems to be two types the physical atom absorbing the light as heat and electrons absorbing light. Could you differentiate the two? $\endgroup$ – Hawkeye Dec 1 '17 at 22:16
  • $\begingroup$ Please read about Absorption spectroscopy. Especially the text below the sketch. Perhaps this makes the things clearer. $\endgroup$ – HolgerFiedler Dec 2 '17 at 6:41
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When light falls on an object, it is partially absorbed, partially reflected, and partially transmitted. Substances absorb only specific wavelengths of light, the other wavelengths are the ones that are reflected/transmitted and are what we see. Objects that we are able to see are poor transmitters and good reflectors of light. Transparent objects such as glass are good transmitters.

A common example are green leaves. Leaves appear green to us because they absorb light falling on them of all the other wavelengths except that of green light. Therefore ideally, if you shine green light on leaves, they won't be able to absorb any energy and as a result start dying.

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