Re: light bulb explosion
From: Richard (spudnuty_at_lycos.com)
Date: 10/19/04
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Date: 19 Oct 2004 15:08:51 -0700
billb@eskimo.com (William J. Beaty) wrote in message news:<2251b4e6.0410181307.454d7b0d@posting.google.com>...
> "PatrickM" <unknown@nospam.com> wrote in message news:<uD0bd.31610$3C6.1147633@news20.bellglobal.com>...
> >
> > Today in our home kitchen a standard 100-watts light bulb "exploded".
>
> I stumbled across the explanation under a Britannica entry for Argon.
>
> Manufacturers put argon in light bulbs as an inert fill gas. Unfortunately
> argon has a low breakdown voltage, so if the filament burns out, an arc
> will leap across the broken ends. So, manufacturers put some nitrogen
> in the argon to raise the breakdown voltage.
>
> But sometimes an arc will strike across the broken filament ends.
> When this occurs, the normal "yellow" light bulb color will turn
> brilliant blue-white for a moment (until the filament is vaporized
> by the arc, and the arc quenches out.
>
> But sometimes the arc continues for too long. Or perhaps the
> manufacturers got the gas mixture wrong. The hot arc will cause
> the argon pressure in the bulb to skyrocket. The bulb will burst
> with a bang.
>
> (A similar thing occurs if you put a bulb in a microwave oven for
> a couple of minutes. The hot plasma inside the bulb will vaporise
> the filament parts, then cause the bulb to explode via overpressure.)
Well that explains a lot! Sometimes when a bulb goes out you can get
it to burn again by flicking it. Sometimes the filament will fuse back
together and it will burn again.
I have seen that brilliant blue-White arc sometimes when a bulb burns
out. It can be quite brilliant and very violent.
We also used to use dichoric glass in front of quartz lamps to change
the color temperature.
Richard
Richard
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