Re: [Phys-l] Microwave door.

[Bernard Cleyet <bernardcleyet@redshift.com>]

All of b's suppositions except deferred are invalid as they are enclosed in steel.   i.e. cap. and short.   So all that's left is running on mt.  I understand (claimed by, IIRC, JD) that the modern ovens include a device to prevent excessive MWs energy from entering the chamber when MT.  Furthermore, glass and, I presume, the plastic door absorbs MWs very little.   So what remains is the air rifle.

bc


On 2010, Dec 26, , at 08:29, brian whatcott wrote:

> On 2010, Dec 23, , at 08:24, Moses Fayngold wrote:
>
> /snip/
> >  I personally have no idea of "Why" and "How" this happened. Of course, I could
> > resort to considering this as a divine message from some mysterious headquarters
> > that it is time for me to switch from pure theoretical to applied physics, but I
> > so far decided to keep such possibility as a last resortMeanwhile, I
> > immediately called to a colleague - a professional experimental physicist with
> > 30 year experience. 
> > Thanks,
> >
> >  Moses Fayngold,
> >  NJIT
> I am late into this question.
>  In  financial and some political (GW?)  and criminal investigations,
>  the rule of thumb is "follow the money".
> In this sort of sudden failure, the ruling idea might be "follow the power".
> A microwave is usually arranged on a rather straight-forward concept.
>  Route line power through a switch and a rectifier diode to a capacitor
>  and magnetron  (which is conceptually, another diode).
>
> Modern microwaves often boast 1.3 KW ratings.
> This amounts to an input current certainly exceeding 11 amps.
>
>
> This power has to be accessible on front panel demand, so the 
> possibility of
> electrical breakdown is always present, even if remote.
> The component best known for explosive failure is the capacitor,
>  and examination  might well have shown this shell was shredded.
>
> Another possibility is a timer failure, so that the device was running
>  on an empty oven.
> This would permit the glass window/reflector to be heated more than usual.
> In this case, you would have expected to hear the mode-strirrer fan 
> rotating.
> If this fan stalls, hot spots result. This is a double failure cascade, so
>  its likelihood is low.
>
> Finally, a short developing in the wiring from the line input might provide
>  a good bang before the high current fuse or breaker  blew.
>  This  blown fuse would have been noted at the time however.
>
> Brian W
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