Bullshit/snake oil alert re electric heaters

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Little John

Post by Little John »

biffvernon wrote:Eh?
You have the unfortunate and deeply irritating habit of peppering the tone of many of your posts with more than a faint whiff of smug condescension and superciliousness B. I am forced to conclude that this must be due to an overinflated consideration of yourself as being significantly wiser and/or more knowledgeable than various others on here. Which may well be the case on a number of occasions, of course. There are other occasions, though, when that will not the case. However, your posts still have the habit of making such an assumption nonetheless. Whilst this tiny little example is, in itself, utterly trivial and, had it been a singular example, I would not even have bothered to comment, it is the fact that is part of a pattern of behaviour in your posts that has caused me to comment and to point out that you really do need to try and control it. This behaviour is irritating not only when you do not have a foundational excuse of it being the case that you are more knowledgeable/wiser, but is irritating even when that excuse may be present. The fact is, it's really not good manners irrespective of any other consideration.

Is your ego really so fragile? You're a grown up. Get a grip man.
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biffvernon
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Post by biffvernon »

stevecook172001 wrote:it's really not good manners
Talking of which...

:roll:
Little John

Post by Little John »

biffvernon wrote:
stevecook172001 wrote:it's really not good manners
Talking of which...

:roll:
I'm simply saying it as I see it B.

Also, you can be assured that if I wish to be bad mannered to my fellow posters, which I try to avoid unless provoked (though non of us are perfect), I will always endeavour to do so transparently and overtly. In other words, I will not hide my bad manners behind a smokescreen of condescension.
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biffvernon
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Post by biffvernon »

Too much heat.
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Post by woodburner »

stevecook172001 wrote:
biffvernon wrote:Eh?
You have the unfortunate and deeply irritating habit of peppering the tone of many of your posts with more than a faint whiff of smug condescension and superciliousness B. I am forced to conclude that this must be due to an overinflated consideration of yourself as being significantly wiser and/or more knowledgeable than various others on here.
Er,.. yup.., but I try to keep up.
This behaviour is irritating not only when you do not have a foundational excuse of it being the case that you are more knowledgeable/wiser, but is irritating even when that excuse may be present.


I am relatively intolerant, but it doesn't irritate me.
The fact is, it's really not good manners irrespective of any other consideration.
Biff is merely giving extra pieces of information, as I see it. As it is your inference that Biff is condescending, it could be just the way you read it. One of the problems of not being able to hear the spoken word.

[/quote]
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biffvernon
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Post by biffvernon »

:)
kenneal - lagger
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Post by kenneal - lagger »

stevecook172001 wrote:
kenneal - lagger wrote:Old vacuum flasks, the proper ones with a double layer of glass with a vacuum between, used to have one side of the glass silvered to prevent radiation heat loss. Just an interesting point.
That was to stop heat being transmitted though the glass, not through the vacuum.

Heat cannot travel through a vacuum. Radiation can travel through a vacuum and, when that radiation encounters a medium, only then may it be transformed to heat.

Whilst the outcome may be functionally equivalent to what has been suggested (that heat itself radiates though a vacuum), the specific mechanism by which that outcome is achieved is not what has being suggested. Heat cannot propagate, unassisted by a medium, through a vacuum. Only radiation can do that.

It is precisely because heat requires a medium of propagation that controlled circulation of heat via such things as convection (in a liquid or gaseous medium) and conduction (in a solid medium) are possible. Have you ever heard of the controlled circulation of light via convection and conduction?
Vacuum flasks, as I said, were silvered to prevent heat being lost by radiation across the vacuum in the vacuum tube. Silvering the glass would not stop heat being transferred through the glass by conduction.The vacuum was there to stop heat being lost by convection and conduction.

I was taught that heat was a form of energy and manifested itself by the degree of vibration of the atoms of the substance heated: the greater the heat the greater the vibration of the molecules. That heat could be transmitted to another body by convection, conduction or radiation or a combination of the three.
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PS_RalphW
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Post by PS_RalphW »

If you want to get technical, the heat is the sum of the vibrational quantum states of the individual molecules, plus the kinetic energy of the gas molecules (if it is a gas) and the electronic eitation levels of the atoms or molecules, and if it is a plasma, the electronic potentials of the released electrons. In crystals it also includes the lattice vibrations called phonons (IIRC) and probably several other modes I have forgotten.

This can lead to interesting properties where, eg, the electronic temperature of gas can be higher than its vibrational or kinetic temperature. The vibrational transition quanta are usually the smallest, so that tends to be the dominant final form all heat energy ends up as. When all the different modes are in equilibrium, I think you end up with what is known as black body radiation.
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Post by biffvernon »

I think you are using the word 'heat' where others would use 'internal energy'. See the link that posted earlier - http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html (and you have to click on 'heat' in the right hand menu).
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mr brightside
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Post by mr brightside »

kenneal - lagger wrote:Even noise ends up as heat as both are just a vibration of molecules.
What do you reckon about the opposing force placed on the frame by the stator magnetic field driving the rotor?

In theory if you removed the motor feet it would roll around the room in a direction opposite to that of the shaft. If we assume it's free to do this unhindered in a circular fashion without striking any objects, would the resulting kinetic energy all still end up as heat?

It reminds me of a time when i was working at the old Allied Colloids plant in Bradford. We'd just rebuilt the bearings on a dumpy little 7.5/2900 Brook Crompton 3~ motor and had connected it to the test supply. We started it direct on-line and it leapt up off its feet and set off down the workshop! You can't beat seeing laws of motion demonstrated like that, Fred Dibnah would surely have approved.
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adam2
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Post by adam2 »

mr brightside wrote:
kenneal - lagger wrote:Even noise ends up as heat as both are just a vibration of molecules.
What do you reckon about the opposing force placed on the frame by the stator magnetic field driving the rotor?

In theory if you removed the motor feet it would roll around the room in a direction opposite to that of the shaft. If we assume it's free to do this unhindered in a circular fashion without striking any objects, would the resulting kinetic energy all still end up as heat?

.
Yes, once the motor has stopped moving, all the energy put into it will end up as heat. mainly due to friction within the motor, friction against the floor, and friction between the surrounding air and the motor.
Whilst the motor is still moving, then of the energy is not yet turned to heat but is kinetic energy. Once movement ceases it all turns into heat.

A very small part of the energy input would end up as noise or vibration, but ultimatly that too is converted into heat. (though a tiny part of the noise might escape and be heard outside of the room, and thereby still be turned into heat, but outside the room)
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