[QUOTE=sltungle;32320898]I was just thinking, if you shine a light through a piece of glass the light is absorbed and[B] remitted by atoms throughout the glass, right?[/B] Why exactly do the photons retain their properties (or information)?
Like let's say I shine polarised light through a window pane: the light will remain polarised once it's passed through the glass... but how? How is this information retained and not lost through electron excitement and remission?[/QUOTE]
wrong, it's not adsorbed at all if it's transparent. if it gets adsorbed there's a colour
[editline]16th September 2011[/editline]
[QUOTE=sltungle;32320898]I was just thinking, if you shine a light through a piece of glass the light is absorbed and[B] remitted by atoms throughout the glass, right?[/B] Why exactly do the photons retain their properties (or information)?
Like let's say I shine polarised light through a window pane: the light will remain polarised once it's passed through the glass... but how? How is this information retained and not lost through electron excitement and remission?[/QUOTE]
wrong, it's not adsorbed at all if it's transparent. if it gets adsorbed there's a colour
[QUOTE=mike;32321476]wrong, it's not adsorbed at all if it's transparent. if it gets adsorbed there's a colour[/QUOTE]
Is adsorbed the correct term? I thought it was absorbed in this context.
Got chemistry on the brain?
[QUOTE=sltungle;32320898]I was just thinking, if you shine a light through a piece of glass the light is absorbed and remitted by atoms throughout the glass, right? Why exactly do the photons retain their properties (or information)?
Like let's say I shine polarised light through a window pane: the light will remain polarised once it's passed through the glass... but how? How is this information retained and not lost through electron excitement and remission?[/QUOTE]
Well, either it makes an electron go up an energy level (which then goes back to the old level and emits a photon with the same energy) or it isn't absorbed at all.
Since electrons can't go in between those shells, the photons has the same energy.
Which is p much what contag said. :v:
[img]http://4.bp.blogspot.com/_R4bDDgSUj2g/R5aXw0QQ89I/AAAAAAAACts/obiir8K40Ss/s400/photon_absorption_large.jpg[/img]
Mike, no mate, not necessarily, if it's transparent, it means a specific system of photons is found first at the start of the material and then at the end of it. being start and end the points at which the system's route intersects the material.
it doesn't really matter whether it isn't absorbed or isn't. As long as the atoms that are hit transmit the same photons, we're in the clear.
What makes the color of a material is the composition of its electron cloud, what makes its transparency is well, fuck, it can't just be whether it absorbs the electron or not, otherwise, a red object would be transparent to blue light.
and by the same model, a black object and a white object both absorb shit, but only the white one spits it out.
I dunno.
[QUOTE=Cree8ive;32320845]True, although I need to get a new notebook for that (not as in computer notebook).[/QUOTE]
Get a big fat refill pad already hole punched and a ring binder. Makes it easy to organise your notes and stuff.
[QUOTE=Contag;32321965]Is adsorbed the correct term? I thought it was absorbed in this context.
Got chemistry on the brain?[/QUOTE]
you are right - it's absorbed not adsorbed.
[editline]16th September 2011[/editline]
[QUOTE=MountainWatcher;32322620]Well, either it makes an electron go up an energy level (which then goes back to the old level and emits a photon with the same energy) or it isn't absorbed at all.
Since electrons can't go in between those shells, the photons has the same energy.
Which is p much what contag said. :v:
[img]http://4.bp.blogspot.com/_R4bDDgSUj2g/R5aXw0QQ89I/AAAAAAAACts/obiir8K40Ss/s400/photon_absorption_large.jpg[/img]
Mike, no mate, not necessarily, if it's transparent, it means a specific system of photons is found first at the start of the material and then at the end of it. being start and end the points at which the system's route intersects the material.
it doesn't really matter whether it isn't absorbed or isn't. As long as the atoms that are hit transmit the same photons, we're in the clear.
What makes the color of a material is the composition of its electron cloud, what makes its transparency is well, fuck, it can't just be whether it absorbs the electron or not, otherwise, a red object would be transparent to blue light.
and by the same model, a black object and a white object both absorb shit, but only the white one spits it out.
I dunno.[/QUOTE]
white things don't absorb anything - they reflect it. black things absorb at all areas of the visible light spectrum.
transparency is absolutely due to photons just passing through it
Photons don't just bounce off the atoms, they're absorbed and then reemitted.
I believe the whole problem would be far easier to understand with the photon behaving as a wave and not a particle. Light reflects from a medium when its refractive index is beyond it's critical angle, and it's refractive index is dictated by the disturbance the electrical field the electrons (amongst other things) emit, thus modifying the wave, the electron never "absorbs" the photon.
MountainWatcher, I understand the concept of absorption and remission, that's not what's bugging me. What's bugging me is how the information related to the polarisation of the light is retained.
A photon with it's E-field and B-field perpendicular to another photon of the EXACT same wavelength has EXACTLY the same energy. It'll excite an electron into the exact same orbital. But why does polarised light go into the atom and come out of the atom still polarised?! Why isn't the outputted light orientated at some random angle?
[QUOTE=MountainWatcher;32330363]Photons don't just bounce off the atoms, they're absorbed and then reemitted.[/QUOTE]
this is not transparency, you're thinking of fluorescence.
[QUOTE=mike;32333978]this is not transparency, you're thinking of fluorescence.[/QUOTE]
No, that's also transparency. If you follow a photon into a plane of glass (or into any material really) it impacts atoms, raises the energy level of electrons in the atoms, and then the atoms then re-emit an identical photon when the electrons drop back down to their ground state. That's why light appears to slow down when it travels through non-vacuum (because this absorbing and re-emitting of photons takes time).
The question I have though is how properties like polarisation can be retained in this process.
[QUOTE=sltungle;32351282]No, that's also transparency. If you follow a photon into a plane of glass (or into any material really) it impacts atoms, raises the energy level of electrons in the atoms, and then the atoms then re-emit an identical photon when the electrons drop back down to their ground state. That's why light appears to slow down when it travels through non-vacuum (because this absorbing and re-emitting of photons takes time).
The question I have though is how properties like polarisation can be retained in this process.[/QUOTE]
god did it
now go to church you heathen
[QUOTE=sltungle;32351282]No, that's also transparency. If you follow a photon into a plane of glass (or into any material really) it impacts atoms, raises the energy level of electrons in the atoms, and then the atoms then re-emit an identical photon when the electrons drop back down to their ground state. That's why light appears to slow down when it travels through non-vacuum (because this absorbing and re-emitting of photons takes time).
The question I have though is how properties like polarisation can be retained in this process.[/QUOTE]
you need to consider this as a wave, not as discrete particles hitting stuff!
polarisation is maintained because every photon isn't being absorbed and re-emitted, it's just passing through as a wave.
interestingly, some molecules emit plane polarised light in a characteristic way, and when they rotate the polarisation of the light changes. which is a fun fact!
wave particle duality
make up your god damn mind, reality
[QUOTE=mike;32357100]interestingly, some molecules emit plane polarised light in a characteristic way, and when they rotate the polarisation of the light changes. which is a fun fact![/QUOTE]
is that the basis behind using polarimeters to distinguish between enantiomers of chiral molecules?
I just started in uni and physics is so much more interesting here, even in just the first 2 weeks, I love it.
[QUOTE=Overv;32363566]I just started in uni and physics is so much more interesting here, even in just the first 2 weeks, I love it.[/QUOTE]
I'm starting uni in a week... to do physics :D
I'm about to take the ACT (about a month from now). I'm told there's a lot of chemistry. I have never had a chemistry class and I'm panicking. Should I self-educate? If so, where do I start?
[QUOTE=Shoupie;32364647]I'm about to take the ACT (about a month from now). I'm told there's a lot of chemistry. I have never had a chemistry class and I'm panicking. Should I self-educate? If so, where do I start?[/QUOTE]
Do you have any idea what chemistry topics are gonna be on the test? It's hard to know what to cover otherwise
[QUOTE=mike;32357100]you need to consider this as a wave, not as discrete particles hitting stuff!
polarisation is maintained because every photon isn't being absorbed and re-emitted, it's just passing through as a wave.
interestingly, some molecules emit plane polarised light in a characteristic way, and when they rotate the polarisation of the light changes. which is a fun fact![/QUOTE]
You don't NEED to think of it as a wave. The wave model is there because it simplifies certain experiments like this one, but you can still treat the light as particles if you really, really want to: it just makes things insanely difficult by comparison..
[QUOTE=Overv;32363566]I just started in uni and physics is so much more interesting here, even in just the first 2 weeks, I love it.[/QUote]
[QUOTE=Turnips5;32363755]I'm starting uni in a week... to do physics :D[/QUOTE]
I was a physics student before it was cool
I want to have Physics as well, but I could only choose one between Biology or Physics. :(
[QUOTE=Cree8ive;32369699]I want to have Physics as well, but I could only choose one between Biology or Physics. :([/QUOTE]
Pretty clear choice.
[QUOTE=Contag;32370411]Pretty clear choice.[/QUOTE]
My aim is to study Biomedical Science so I "had" to choose Biology over Physics.
I love both, but can't have them both.
The IB is being mean to me...
[QUOTE=Cree8ive;32372619]My aim is to study Biomedical Science so I "had" to choose Biology over Physics.
I love both, but can't have them both.
The IB is being mean to me...[/QUOTE]
Ah, well in that case, that's more reasonable.
Which field of biomedical science do you plan to specialize in?
[QUOTE=Contag;32372975]Ah, well in that case, that's more reasonable.
Which field of biomedical science do you plan to specialize in?[/QUOTE]
Not sure what to specialize in, but time will tell. Looking at either virus or bacteria for now.
God damn OP amps and their offset bullshit are driving me crazy!
Anybody got that down?
I wish schools here had Astronomy class.
the science portion of the ACT is reading graphs
its a joke
[QUOTE=Jo The Shmo;32379466]the science portion of the ACT is reading graphs
its a joke[/QUOTE]
good preparation for physical chemistry then.
And I'm studying 4 sciences for A Level (AS), Biology, Chemistry, Physics and Geology. To be honest Physics hasn't been as bad as I thought it would be, not liking chemistry a huge amount though.
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