Re: OT: They don't make 'em like they used to

Diesel Damo wrote:

><http://www.breitbart.tv/?p=90303>
>
>108-year-old light bulb - yes, it still works.

So long as you don't mind the faint red glow of a carbon filament
light bulb.  Most people simply chucked them away and replaced them
with tungsten long before they got broken.

They had a stack of 'em in the physics lab when I was at high school
(or was it uni) somewhat less than 108 years ago.  The reason they had
them was to demonstrate their negative temperature coefficient of
resistance (NTC) -- ie the resistance decreases as they warm up, which
is exactly the opposite of a tungsten filament.

It is of course the reason why the old carbon filaments didn't often
burn out whereas tungsten filaments do....  Perhaps you've never
wondered why a tungsten filament light bulb only ever blows when you
switch it on (in the absence of vibration or bumping)!  You should
also note that this one's hanging on a cord (which protects it from
vibration and mechanical shock).

Which all goes to show you can actually learn something useful (well
almost) in a physics class.  :)

-- 
John H