hysteresis. Nuclear spin is an atomic level property and does not enter int o chemical bonding to form molecules. If there were hysteresis MRI scans w ould heat up your body and do harm.
. You have completely the wrong process. Do some reading. It will do you good.
He's not talking about water but rather ferrites, where hysteresis is impor tant.
The ignorance is all yours.
-- Bill Sloman, Sydney
When you read something about the actual topic of conversation, the absorpt ion of microwaves by water, I will read up on magnetization of iron which i s NOT the topic of conversation. Not sure why you are talking about magnet ic domains, water is not magnetic.
Please, read something. I even made it easy for you with a link.
Until then, I guess this conversation is over. Learn or remain ignorant. Your choice.
-- Rick C. ---+ Get a 1,000 miles of free Supercharging ---+ Tesla referral code - https://ts.la/richard11209
te:
o hysteresis. Nuclear spin is an atomic level property and does not enter i nto chemical bonding to form molecules. If there were hysteresis MRI scans would heat up your body and do harm.
on. You have completely the wrong process. Do some reading. It will do y ou good.
ortant.
Lol! You, like him, brought a knife to a gun fight. The topic of conversa tion was absorption of microwaves by water. I don't know why you are talki ng about magnetic domains. Try to stay on topic, please?
-- Rick C. --+- Get a 1,000 miles of free Supercharging --+- Tesla referral code - https://ts.la/richard11209
But those studies were done *decades* ago, AlwaysWrong. They must not be valid anymore, right, AlwaysWrong?
It certainly was, AlwaysWrong. You're still wrong - always, DimBulb.
snipped-for-privacy@gmail.com wrote in news: snipped-for-privacy@googlegroups.com:
No, asswipe. The topic was about hysteresis, the action by which resistance to domain flipping generates heat.
The mention of iron was to teach you about the effect. Which you are obviously still 100% clueless about.
It is not about a medium such as water "absorbing" microwave energy, it is about the magnetic domains generating heat.
Flipping a few cells at 27MHz does nothing or next to nothing. Fliping them at 2.5GHz does cause heating because the molecules are reluctant to flip that fast.
A low frequency transmitter makes it through water. A high frequency transmitter cannot.
Navy seals that need to communicate with each other while underwater must use very low frequency transmitters as the attenuation of the water is high.
Now guess why.
snipped-for-privacy@notreal.com wrote in news: snipped-for-privacy@4ax.com:
No, idiot. Just like the studies that resulted in 63/37 solder. We know what we are doing despite the presence of retarded gum up the works asswipes like you.
Navy Seals had to communicate through salt water, which is conductive. That had quite a lot to do with the choice of transmission frequency.
Molecular deformations didn't come into it.
-- Bill Sloman, Sydney
snipped-for-privacy@ieee.org wrote in news: snipped-for-privacy@googlegroups.com:
EM travels through salt water or fresh water very similarly. In both a lower than 'normal' 'rf' frequency must be used in order for the EM wave to propagate very far. Seals only need to comm to each other over say a 60 ft diameter span. The frequency is not low because of salt water or fresh water. It is low because water attenuates higher frequencies almost completely. Unlike the VLF they use to comm huge expanses (with huge power), this only needs to make it a short distance but needs to be high enough to pass data at a reasonable rate.
I do not know about deformations for low frequency radios or anything else. I never said anything about 'deformations'.
snipped-for-privacy@gmail.com wrote in news: snipped-for-privacy@googlegroups.com:
Yes, the hystresis of the water at the operating frequency and power generated in the microwave cavity generates heat in the medium. Said medium is the water. Other than water molecules also respond. That is why certain dishes cannot be used.
That is EXACTLY what I stated takes place. Hysteresis is the mechanism. Electromagnetic hysteresis. Real simple.
Toggle, toggle. Toggle too fast and things warm up. Call it friction if you are having a hard time getting it.
snipped-for-privacy@gmail.com wrote in news: snipped-for-privacy@googlegroups.com:
Look, dude. You say "absorption". You also say that the domains flip free of cost.
I say the "absorption" is the heat generated by the water's LACK of ability to respond to the domain flip influence.
So you lie about the cost of domain flipping (which you claimed costs nothing) or you have no clue what the term "absorption" means as it relates to rf energy, or you are clueless about it. I say you are clueless. You cannot lie about what you are too clueless to understand.
Actually, it isn't. Hysteresis hasn't got anything to do with with what wat er does when it absorbs (and re-radiates) electromagnetic radiation.
You've either got excited states or you haven't. Hysteresis if a feature of magnetisable materials, which water isn't.
t is
But wrong.
Simple molecules have excited states. When more of them are in an excited s tate they are warmer - the quantum-mechanical definition of temperature is the proportion of of the molecules that are in an excited state (as opposed to the ground state).
There are vibrational excited states - stretches and bends - and rotational excited states. In condensed states - liquids and solids - where molecules are close enough to interact for longer than the vibrational and rotationa l periods - you get lots of low-energy excited states covering a wide range of relatively low frequencies.
"Toggling" doesn't come into it. For that you need magnetic materials, whic h have rather more complicated behaviours.
-- Bill Sloman, Sydney
There aren't any "domains" in water.
Sadly, you have confused what goes on in magnetic materials (which do have domains and hysteresis) when exposed to electromagnetic radiation with what happens in non-magentic materials like water (which don't).
He isn't lying - and neither are you - but you do happen to be wrong.
I got some very tedious lectures on the subject in the first year of my pos tgraduate course - statistical mechanics or the like - and you need to find something similar. I've no idea where you'd get it these days - I got my l ectures in 1963, which is more than fifty years ago. I met the lecturer aga in a year or so ago at some fifty years on get-together, but he's in Melbou rne, Australia.
-- Bill Sloman, Sydney
My limited knowledge is that water has *no* special absorbtion or peaks or notches at 2.45GHz. Nothing magic about 2.45GHz. That frequency is used simply because it is an ISM band and interference has to be tolerated. Some microwave ovens use quite different frequencies, again chosen for EMC reasons rather than atomic effects.
piglet
yeh it isn't by accident that the common microwave frequencies is in the middle of ISM bands
frequency they are at.
Don't know what you mean by "magic". That frequency is ISM because it is u sed in microwaves. From wikipedia, "The ISM bands were first established a t the International Telecommunications Conference of the ITU in Atlantic Ci ty, 1947. The American delegation specifically proposed several bands, incl uding the now commonplace 2.4 GHz band, to accommodate the then nascent pro cess of microwave heating".
The "magic" for using this frequency is simply that it is a frequency that is strongly absorbed by water and a frequency that was not so hard to gener ate at the time they started. In other words, good enough.
-- Rick C. -+-- Get a 1,000 miles of free Supercharging -+-- Tesla referral code - https://ts.la/richard11209
he frequency they are at.
used in microwaves. From wikipedia, "The ISM bands were first established at the International Telecommunications Conference of the ITU in Atlantic City, 1947. The American delegation specifically proposed several bands, in cluding the now commonplace 2.4 GHz band, to accommodate the then nascent p rocess of microwave heating".
t is strongly absorbed by water and a frequency that was not so hard to gen erate at the time they started. In other words, good enough.
This seems to say the same.
The rotational spectrum dips into the GHz. (any frequency would do.) I'm guessing some thermal - rotational thing. Is heating ice less efficient?
George H.
yes, that why the defrost program cycles the microwave on and off
ON for while to heat whatever liquid water there is, OFF to let that water melt some more ice and not cook whatever it is you are defrosting
-Lasse
Huh, there ya go.
Microwaves can't heat ice... we can all do the experiment!! (sorry I'm in the middle of HPMOR, which I'm going to describe as a mix of JK. Rowling, D. Hofstadter, and T. Pratchet, for sci-fi geeks it's great! If you haven't read any HP, then just read the first book.)
George h.
Right. I guess I never understood that before.
(I don't use the microwave much, but seems like a liquid bath may help.)
GH
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