"Dr Ivan D. Reid" wrote in message
...
On 9 May 2006 04:10:38 -0700, Norbet
wrote in . com:

We have a microwave oven that has some small paint chips inside the
oven under the turntable. We're not sure if this constitutes damage or
not (it appears to be bare metal beneath the paint and I always thought
that was a bad thing for microwaves but I could be wrong). It still
cooks fine and doesn't appear to spark or anything during use.

Could a small paint chip affect the safe operation of a microwave oven?

No. The paint is only a cosmetic covering over the metal cavity
of the microwave oven. There should be no risk of sparking as the cavity
walls are nulls in the standing-wave pattern. The only place you should
normally be concerned with leakage of a microwave is at the door seal --
assuming no-one has been silly enough to interfere with the magnetron
feeding the cavity. Dirt on the seal or damage could allow leakage but
given that the wavelength is about (3x10^10/2.45x10^9)=12.2 cm, you need
a fairly large gap to get any significant leakage -- consider the size of
the holes in the door-screen which allow you to see into the oven but do
not
let any microwaves escape.

Huuummm, interesting, Ivan; is it possible to pad the cavity out so altering
its resonant frequency, and furthermore is it also possible to give some
idea what kind of modulation transformer would be needed so that one could
use the oven as a source on 23 cms for EME? ;-}

Dave Doubleyew. ( G3F**.)