13 Dec
2004
13 Dec
'04
4:57 p.m.
>>>> "Carlos" == Carlos Murillo
<cmurillo(a)manizales.autonoma.edu.co> writes:
> 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 ).
Carlos> Ah, the "Edison Effect". Some electrons (especially those
Carlos> closer to the negative side) would jump away from the
Carlos> filament and then, thanks to the electric field, land on the
Carlos> filament but closer to the anode. The result was that the
Carlos> section of the filament closer to the anode would be carrying
Carlos> more current than say, the first third of the length of the
Carlos> filament (in the - towards + direction). So filament
Carlos> failures almost always occured in the last 1/3 of the
Carlos> filament. ...
Interesting! That suggests that DC should be no big problem for
halogen lamps (incandescents with iodine vapor fill).
paul