Resonance Energy

Discussion in 'General Electronics Chat' started by aymanok, May 23, 2014.

  1. aymanok

    Thread Starter New Member

    Jul 10, 2012
    1
    0
    What is the resonance energy of water ( joule/mole)
    are there tables or equations for calculations?
     
  2. wayneh

    Expert

    Sep 9, 2010
    12,078
    3,014
    You could look here.

    Or you could start with better defining the term. I've had several graduate level thermodynamics classes and I've never heard the term.
     
    Last edited: May 23, 2014
  3. studiot

    AAC Fanatic!

    Nov 9, 2007
    5,005
    513
    This is one for Bertus, it is his area.

    Alternatively note that a microwave oven heats up the water in the food.

    Yes, that is a resonance phenomenon where the microwave energy is absorbed by the OH bonds in the water molecule.

    The energy involved is given by the usual Plank relationship.

    There are other bond resonances in water, so you will actually need to specify which one.
     
  4. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
    1,305
    Is that really a "water resonance"??

    Heat also heats up water in the food, and that is a different wavelength(s) than a MWO magnetron.

    I thought the heating effect was simply a result of hitting the food with enough energy?
     
  5. t06afre

    AAC Fanatic!

    May 11, 2009
    5,939
    1,222
    Is this question related to some sort of energy production from water? If so I would recommend you to drop your plans rather sooner than later
     
  6. bertus

    Administrator

    Apr 5, 2008
    15,634
    2,342
  7. studiot

    AAC Fanatic!

    Nov 9, 2007
    5,005
    513
    I mentioned Bertus because of the MRI connection.

    No the microwaves in a microwave oven are specific to the OH bond, they will not heat up food material that does not contain these bonds.

    Note, some other molecules such as sugar and starch also have these bonds and can be heated this way. Note the effect on a mince pie.

    The specifity is the reason it is a resonance effect. Resonance is an effect where the transfer of energy from one system to another is greatly enhanced by supplying the energy at the appropriate frequency. (Micorwave in the case of water).

    There is no mystic energy gain due to resonance.
    So I agree if the OP is about overunity this thread is invalid and should be closed.
     
  8. bertus

    Administrator

    Apr 5, 2008
    15,634
    2,342
  9. alfacliff

    Well-Known Member

    Dec 13, 2013
    2,449
    428
    microwave ovens used to work at a frequency near the resonance of water, aprox 2.4ghz. now they run at 900 mhz or so, it is cheaper to make power there. rf heating is actually at any frequency, just most heat at near 2.4 ghz. when you look at the FCC webpabe, they have standards for maximum rf exposure limits.
     
  10. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
    1,305
    That sounds more like it. :)

    Sorry Studiot I'm not buying the "microwave oven resonant frequency of water" theory. It's just lots of energy into an enclosed space.

    Out of curiosity I have a white ceramic bowl that heats up faster than the food in the MWO. It's lousy for defrosting but great for cooking. And can be painful to remove from the oven!
     
  11. bertus

    Administrator

    Apr 5, 2008
    15,634
    2,342
    Hello,

    When the bowl contains any metal parts, it will heat up very fast.
    Thats why you can not use metal parts in a microwave oven.

    Bertus
     
  12. nsaspook

    AAC Fanatic!

    Aug 27, 2009
    2,902
    2,150
    It's a lot of energy in a enclosed with a molecule (water) that's a good dielectric with a lopsided charge distribution. The water molecule rotates as the electric fields changes so now you have voltage, current (charges in motion) flow and power that mainly seen as resistance heating of the food and water. There are frequencies where the rotation speed matches the rate of voltage change so just as the molecule spins one way the field reverses and pushes it around in a circle like a flywheel.
     
  13. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
    1,305
    Interesting! I've never heard that.

    But if the water molecule has a natural "rotation speed" roughly in sync with the microwave energy (ie "flywheel") wouldn't that be MORE efficient, and cause LESS heating?

    I thought heating occurs in a substance is a repsonse to poor efficiency? So if you bash on a spring at resonance it is efficient and doesn't heat the spring very much. Energy is input, and then returned. But if you bash on a lump of clay it is very inefficient and causes the clay to heat?
     
    #12 likes this.
  14. studiot

    AAC Fanatic!

    Nov 9, 2007
    5,005
    513
    That's all there is to resonance. Perhaps I should have said that the energy supply needs to be continued (not continuous).

    A single 'bash' can never be a resonance phenomenon. A coordinated series of bashes can, and are probably the easiest way to explain resonance.
     
  15. #12

    Expert

    Nov 30, 2010
    16,238
    6,722
    I can certainly see the logic in RB's argument.
    (That doesn't mean I know how it works.)
     
  16. studiot

    AAC Fanatic!

    Nov 9, 2007
    5,005
    513
    If you bash something with a hammer, it does not matter what material you bash with it. The response is, in general, the same.

    However it is easy to prove that microwaves are selective in their effect on materials.

    Understanding resonance is one issue.

    Understanding how that allows electromagnetic energy to be transferred to some material object is another.

    Understanding how this energy ends up as heat is yet another.

    Since we seem to have left the OP far behind I am quite happy to explain the chain of events connecting these three issues.
     
    Last edited: May 26, 2014
  17. #12

    Expert

    Nov 30, 2010
    16,238
    6,722
    Don't do it on my account. I'm just happy I can have a hot cup of coffee in about 2 minutes.:p
     
  18. nsaspook

    AAC Fanatic!

    Aug 27, 2009
    2,902
    2,150
    My response was a simplification of a much more complex process of energy transfer by rotational torque. Resonance increases the absorption efficiency. If you bash a lump of clay how much energy is in the clay and how much energy is actually transfered to the surface the clay as resting on?

    Each water molecule is only in sync to the phase of the RF energy at it's location so across the material a gradient (time-dependent field) of voltage and current peak vibrations form that act as antennas to absorb and re-emit the energy that's converted to heat. This gradient also causes hot spots in food so we see turntables for better uniformity in heating.

    http://faculty.trinityvalleyschool.org/hoseltom/labs/Lab-27-(Heating Water with Microwaves).pdf
     
  19. studiot

    AAC Fanatic!

    Nov 9, 2007
    5,005
    513
    It is probably worth pointing out that the term (noun) resonance refers to the whole process.

    The term (adjective) resonant refers to the ability participate in the phenomenon of resonance.

    So we have a resonant system that can resonate.
    We have resonant frequency, the frequency of the energy exchange
    and so on.
     
  20. wayneh

    Expert

    Sep 9, 2010
    12,078
    3,014
    And the OP was likely hoping to split water "for free" (which can't ever be done) by zapping it at the right frequency, which is well into the terahertz and so can't be done with current technology even if it was free, which it is not.
     
Loading...