13 Dec
2004
13 Dec
'04
9:55 a.m.
From: "Tom Jennings" <tomj(a)wps.com>
On Mon, 13 Dec 2004, Carlos Murillo wrote:
I'd heard of the effect, but not for a long time, and probably paid little
attention to it :-)
So, how pronounced is this DC-filament effect? If I collect
dead lightbulbs from my cars, should I see filaments with gaps
burned towards the ground end more often than not?
(Tapered filaments would fix this.)
Hi
I would think the effect is smaller today since we don't
still use high vacuum bulbs. Most have a partial atmosphere
of an inert gas. The Edison effect is the same as used
in vacuum tubes. You still might see a slight bias towards
one or the other end.
You have to realize that work hardening and fracturing
of the filament in an auto is a large factor in shortening
the life of these lamps.
Dwight
It
isn't much good for home use. In fact, lamps don't
do as well on DC as AC because of the electrical effects
of the wire evaporating ( not sure which end goes first ).
Ah, the "Edison Effect".