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Old Jun 28th 2018, 02:23 AM   #11
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Avito, it seems the title of your thread has confused people.

So... to clarifiy... if we're talking about the photons emitted when orbital electrons in an atom transition to lower level states, then the source of the energy is the Coulomb potential energy.

If you're talking about microwave radiation in general, then the usual source of them is not typically orbital electron transitions. A more typical source is molecular bond de-excitation, whereby the energy comes from kinetic energy (wrapped up in, for example, vibrational modes).

If you're talking about microwave ovens, orbital electron transitions are not really a relevant phenomenon. The contents of the oven are heated due to dielectric heating, not frictional heating... *glares at Thermo*.

There is no mass-energy conversion in any of these phenomena.

Last edited by benit13; Jun 28th 2018 at 03:08 AM.
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Old Jun 28th 2018, 05:02 AM   #12
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Elaborate.

Originally Posted by benit13 View Post
A more typical source is molecular bond de-excitation, whereby the energy comes from kinetic energy (wrapped up in, for example, vibrational modes).
I might be misinterpreting this but if I am wrong correct me.

By molecular bond de-excitation you mean that the water molecule has a polar charge and when it comes in contact with the microwave then the bond de-excites and the hydrogen atoms flip over say 5 billion times in a minute and this kinetic energy constitutes the temperature?

Is this referencing dipole rotation?
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Old Jun 28th 2018, 05:19 AM   #13
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Avito,

Do you only ever look at the last post before you reply?


Or do you just not care what the correct answer to your question is?


Or was there something you didn't like in my (correct) explanation?


If so please tell me so I can avoid offering help ever again.
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Old Jun 28th 2018, 12:53 PM   #14
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Originally Posted by benit13 View Post
There is no mass-energy conversion in any of these phenomena.
Polite cough.
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Old Jun 29th 2018, 02:49 AM   #15
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Originally Posted by avito009 View Post
I might be misinterpreting this but if I am wrong correct me.

By molecular bond de-excitation you mean that the water molecule has a polar charge and when it comes in contact with the microwave then the bond de-excites and the hydrogen atoms flip over say 5 billion times in a minute and this kinetic energy constitutes the temperature?

Is this referencing dipole rotation?
Molecules can generally do the following

1. Translate (molecule moves around)
2. Vibrate (components of molecule move relative to each other)
3. Rotate (molecule rotates)

Using these three modes, there are different ways in which a molecule can gain (become excited) or lose kinetic energy (de-excite). It's important to consider these when thinking about heat capacity, solid state physics or radiation because many phenomena are tied to these modes.

When a molecule is in an excited state (i.e. doing some of the three things above) and it then de-excites to a lower energy, it is sometimes possible for the energy to be converted to radiation. If you observe the radiation emitted by diatomic gases, you often find emission or absorption spectra because the bonds in the molecules are contributing to the spectra just as much as the energy levels of the orbital electrons.

Dipole radiation is just a little bit different. The above stuff can happen with any molecule, whereas dipole radiation only happens with dipoles.

Last edited by benit13; Jun 29th 2018 at 02:56 AM.
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Old Jun 29th 2018, 04:21 AM   #16
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In threads like this one its important to know all about the idea of what energy is. That's why I wrote this: What is Energy?
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Old Jun 29th 2018, 05:58 AM   #17
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Originally Posted by Pmb View Post
In threads like this one its important to know all about the idea of what energy is. That's why I wrote this: What is Energy?
IMHO it feels like a work-in-progress Pete. I'm pleased to see you mention the Poynting vector in the electron context. But I think you should think about Compton scattering too.


Image from Rod Nave's most excellent hyperphysics

You can convert some of the photon's E=hf wave energy into electron kinetic energy. Then you could do another Compton scatter using the residual photon, and another and another. In the limit you have removed all of the wave energy, and there's no wave energy left. Hence there's no wave left. Hence you have converted that photon into the kinetic energy of electrons.

But wait: you could have put that photon into gamma-gamma pair production, and used it to create an electron. This is why an electron is quite literally made out of kinetic energy. It's why matter is made of energy. It why energy isn't just some book-keeping thing. I'll be putting all this stuff up on the internet in the coming weeks and months. See for example how gravity works.

Last edited by Farsight; Jun 29th 2018 at 06:01 AM.
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Old Jun 29th 2018, 07:46 PM   #18
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The atom has less mass once the energy photon has been released.
So the energy comes from the atoms mass. The photon must be
between the nucleus and the electron keeping the electron at the higher energy
shell level. I believe the electron has captured the photon. This raises the
electrons frequency and its energy according to Planck constant.

Woodys tensor I believe is this added photon energy?
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Old Jun 30th 2018, 10:42 AM   #19
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Originally Posted by Farsight View Post
...This is why an electron is quite literally made out of kinetic energy. It's why matter is made of energy...
OUCH!! Nothing is made out of pure energy, kinetic energy or otherwise. Matter is not made of energy. Keeping things simple, most of the time in QM when you have a collision there usually is energy converted from mass. That does not mean that energy is mass just as energy isn't enough to describe a particle... particles have various properties: energy, momentum, charge, weak hypercharge, and spin to name a few. Pure energy would not.

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Old Jun 30th 2018, 01:24 PM   #20
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I still think this has veered wildly off topic and also away from the high school level it is asked at.


The original question contains one misconception and one very good question which I have already praised.

The misconception is that microwave radiation is due to electron orbital transitions.
It is not.

For instance a sheet of lead emits approximately 412 watts per square metre of infra red and microwave radiation at a temperature of 20 degrees centigrade.

None of this is due to electronic orbital transitions or indeed due to electrons at all.


Thus my question is:

Is this about microwaves or radiation emitted/absorbed in the course of electronic obital transitions?
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Last edited by studiot; Jul 2nd 2018 at 12:44 PM. Reason: spelling
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