Resonating molecules
Question:
Can you tell
me the resonating frequency of H
2O (water) and how resonance in atoms work so
I could get a broader understanding of resonance in atoms.
Answer:
I think it is best dealt with in two parts.
Firstly
the resonance of some diatomic molecules.
Hydrogen chloride 8.66x10
13
Hz
Carbon monoxide 6.42x10
13 Hz
Nitrous oxide
5.63x10
13 Hz
You can look up theory of how these frequencies are
calculated in university text books such as Physics by R.Serway. It is way above A level
however.
These frequencies lie in the near infra red part of the spectrum, nowhere near
the microwave area.
Now to water and microwaves.
When microwaves pass
through water the water molecules twist and turn, writhing around, as they pass. However
after the microwaves have gone the molecules stop moving again, remitting the energy as
more microwaves. In free water molecules this does not result in a heating. It is the rubbing
of one molecule against another as in liquid water that allows the energy to be retained and
prevents it being reemitted as microwaves.
Microwave ovens operate at a frequency
of 2.45 GHz and this is NOT the resonant frequency of a water molecule. If it were the
microwaves would all be absorbed in the surface layer of a substance (liquid water or food)
and so the interior of the food would not get cooked at all.
The 2.45 GHz is a kind of
useful average frequency. If the frequency was much higher then the waves would penetrate
less well, lower frequencies would penetrate better but are absorbed only weakly and so
once again the food would not absorb enough energy to cook well.
If you want to
look at a really good site with a moving applet try
this:
http://www.colorado.edu/physics/2000/applets/h2o.html
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