🚀 go-pugleaf

ornitz@kodak.kodak.com (Barry x24904/ER/167B-TED) writes:
> In article <1993Jan26.125656.29958@doug.cae.wisc.edu> kolstad@cae.wisc.edu 
> (Joel Kolstad) writes:
> >Microwaves are tuned to heat up water most effectively, so things with
> >little water in them (i.e., non-microwave popcorn) don't cook well.
> 
> I agree with almost everything said but this.  Microwave ovens are NOT
> specifically tuned to any resonant absorption frequency of water.  Water
> happens to be a good absorber over a broad range of frequencies.  The choice
> of 2.45 GHz (in the US) for the operating frequency of home microwave ovens is
> more an economic one and one dictated by international agreements.  915 MHz
> is often used industrially in the US, and a myriad of other frequencies are
> used in foreign countries.
> 
> This is a common misconception, and one that even tends to be propagated by
> physics professors who should know better.  Water absorbs considerable
> energy at frequencies used in microwave ovens, but so do many other materials.
> 
> For those who want further references, the best I can suggest is "Microwave
> Spectroscopy" by Charles Townes and Arthur Schawlow. [Remember that before
> the laser came the maser which was an offshoot of Townes work with microwave
> spectroscopy!]
> 
> Let's kill the myth that microwaves heat only water and that the frequency is
> a special one that resonates with water molecules.
> 					Barry
>  -----------------
> |  ___  ________  |    Dr. Barry L. Ornitz          WA4VZQ
> | |  / /        | |    Eastman Chemical Company
> | | / /         | |    ECC Research Laboratories, Engineering Research Div.
> | |< < K O D A K| |    Process Instrumentation Research Laboratory
> | | \ \         | |    P. O. Box 1972, Building 167B
> | |__\ \________| |    Kingsport, TN  37662  (615/229-4904, FAX 615/229-4558)
> |                 |    INTERNET:   ornitz@kodak.com
>  -----------------


I agree, adding almost anything to water causes it absorb more energy and
heat faster. Try a glass of tap water and a glass of tap water with 3 Tbs
of sugar in it, I'm sure the sugar water will heat faster. The fat content
of foods also affects the max. temperature that can be acheived. The
manufacture of RubberMaid products states that high fat foods when
microwaved in their products can blister the plastic on the inside of
the container.
 As far microwaves heating unevenly, *they don't*, its just that the food,
depending on its shape, density, fluidity, etc. do not dissapate the head
evenly and consequently hot spots form (from experience you will find that
a hot spot will never form in the center of food object being heated).

Peter Walsh
Hewlett Packard
pjw@col.hp.com