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Asked by doppler to Adam, Geoff, Rob, Sheila, Suzie on 22 Mar 2011 in Categories: General.
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Suzie Sheehy answered on 21 Mar 2011:
Hi there, when photons travel through glass they actually travel through it, rather than being absorbed by electrons. Sometimes though if photons interact electrons and the electrons re-emit a photon, it will always be at the same wavelength (because of the electron jumping between energy levels in the atom) – but not necessarily the same wavelength that was sent in!
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Robert Simpson answered on 22 Mar 2011:
When photons travel through materials they pretty much just travel through them. They are moving through the electromagnetic field, rather than the material itself.
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Adam Tuff answered on 22 Mar 2011:
Off the top of my head I don’t know – I’d imagine that’s where our conservation laws play a big roll – momentum particularly!
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Sheila Kanani answered on 22 Mar 2011:
I think it is because photons actually travel right through the glass…..
Comments
doppler commented on :
Thank you for your answer, Suzie! So is it because the electrons in the structure of glass interact so weakly with photons (at visible frequencies) that glass appears transparent, rather than any ability of the electrons to absorb and then re-emit photons in the same direction? If so, why is this?
Suzie commented on :
Visible light photons can go through glass because the electrons in the glass are tightly bound to the atoms. The electrons need more energy than the photon has to kick the electron to a higher energy state, so it doesn’t absorb the photon. If you change the wavelength of the light or the composition of the glass then it will become ‘opaque’ and could absorb the photons.
doppler commented on :
Thank you, that’s really interesting! In that case does most matter become more opaque at higher frequencies?
Suzie commented on :
Yep matter usually acts differently at different frequencies. The same stuff happens out in the Universe – some objects are opaque at some frequencies!