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  4. Do you change the spectrum of radiation inside an oven if you change its shape?
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Do you change the spectrum of radiation inside an oven if you change its shape?

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Offline Bored chemist

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Re: Do you change the spectrum of radiation inside an oven if you change its shape?
« Reply #60 on: 21/03/2023 13:22:09 »
Quote from: hamdani yusuf on 21/03/2023 12:05:04
Quote from: Bored chemist on 20/03/2023 17:42:32
Quote from: hamdani yusuf on 20/03/2023 17:38:21
Quote from: Bored chemist on 20/03/2023 17:24:25
What's the metal?
I don't know. There's not enough information to distinguish one from the others.
But you said there was.
Quote from: hamdani yusuf on 20/03/2023 04:13:31
They are good enough to distinguish the absorption spectrum of gold from silver. If their difference in emission spectrum of gold and silver is proportional to the difference in absorption spectrum, then cameras and TV screens should be able to distinguish them as well.
They can distinguish the difference in absorption spectrum.
Is this false?
Can't you see the difference?


We can all see the difference.
But that difference is between the reflectance spectra, not absorbance or emission..

I don't think any of us can see the relevance of your original pictures of the molten metals.
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Offline Bored chemist

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Re: Do you change the spectrum of radiation inside an oven if you change its shape?
« Reply #61 on: 21/03/2023 13:26:44 »
Quote from: hamdani yusuf on 21/03/2023 13:13:11
Your conclusion was, molten gold emits more blue light than  molten silver, because gold absorbs more blue light when they are cool.
My view is that the electronic band structures don't change much on heating to the melting point(s).
And we know that silver is a good reflector.
We know (from the conservation of energy) that that means it can not be a good absorber.
And we know (from Kirchhoff's work) that it can not be a good emitter.

For red light, the same is true of gold.
But, for blue light we know that gold is not a good reflector.
It is a relatively good absorber and we  therefore know it is a relatively good emitter.

None of this is anything other than 19th century physics.
Why are you arguing about stuff that has been known for all that time?
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Offline alancalverd

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Re: Do you change the spectrum of radiation inside an oven if you change its shape?
« Reply #62 on: 21/03/2023 14:07:25 »
Problem with the above images of molten metals is one of dynamic range. It's clear that the image receptor is saturated and therefore unable to resolve any spectral information. A dense filter might resolve differences between  two metals at the same temperature precisely because they aren't "black" at any temperature, but you wouldn't be able to see anything else in the picture.

Also worth noting that digital image receptors (cameras, phones, etc) use fixed filters to replicate human visual response in addition to any removable physical or computational filters that the user might add.
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Offline hamdani yusuf

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Re: Do you change the spectrum of radiation inside an oven if you change its shape?
« Reply #63 on: 21/03/2023 15:49:21 »
Quote from: Bored chemist on 21/03/2023 13:22:09
We can all see the difference.
But that difference is between the reflectance spectra, not absorbance or emission..
What happens to the unreflected light?
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Offline Bored chemist

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Re: Do you change the spectrum of radiation inside an oven if you change its shape?
« Reply #64 on: 21/03/2023 17:55:05 »
Quote from: hamdani yusuf on 21/03/2023 15:49:21
Quote from: Bored chemist on 21/03/2023 13:22:09
We can all see the difference.
But that difference is between the reflectance spectra, not absorbance or emission..
What happens to the unreflected light?
Quote from: Bored chemist on 21/03/2023 13:26:44
And we know that silver is a good reflector.
We know (from the conservation of energy) that that means it can not be a good absorber.
There are two sorts of people in the world.
One sort can extrapolate from incomplete data.
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Offline hamdani yusuf

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Re: Do you change the spectrum of radiation inside an oven if you change its shape?
« Reply #65 on: 22/03/2023 13:21:21 »
Quote from: hamdani yusuf on 21/03/2023 15:49:21
Quote from: Bored chemist on 21/03/2023 13:22:09
We can all see the difference.
But that difference is between the reflectance spectra, not absorbance or emission..
What happens to the unreflected light?
Let me help you to answer my question, just in case you are having difficulty.
It's absorbed. Which means that absorbed spectra between gold and silver in room temperature are different.
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Offline Bored chemist

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Re: Do you change the spectrum of radiation inside an oven if you change its shape?
« Reply #66 on: 22/03/2023 17:11:42 »
Quote from: hamdani yusuf on 22/03/2023 13:21:21
Let me help you to answer my question,
I did.
Quote from: hamdani yusuf on 22/03/2023 13:21:21
just in case you are having difficulty.
I wasn't.
Quote from: hamdani yusuf on 22/03/2023 13:21:21
absorbed spectra between gold and silver in room temperature are different.
That's exactly why I referred to the use of gold.

Let me know when you catch up.
Quote from: Bored chemist on 21/03/2023 13:26:44
My view is that the electronic band structures don't change much on heating to the melting point(s).
And we know that silver is a good reflector.
We know (from the conservation of energy) that that means it can not be a good absorber.
And we know (from Kirchhoff's work) that it can not be a good emitter.

For red light, the same is true of gold.
But, for blue light we know that gold is not a good reflector.
It is a relatively good absorber and we  therefore know it is a relatively good emitter.

None of this is anything other than 19th century physics.
Why are you arguing about stuff that has been known for all that time?
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