A simple question, what causes bulbs to go black after a short time ie: tail lamp ?? A fault or quality of bulb.
Sooty
A simple question about - Bulbs
Moderator: RichardW
Bulbs go black as the tungsten filament "boils off" as a vapour and is then deposited on the glass as a dark stain. So the black was once part of the filament. The tungsten is glowing white hot in order to give the needed light. IF it goes black in a short space of time it is most likely that the applied volts are too high - so running the filament at a higher temperature than is desirable causing premature blackening. Cheap bulbs could be so poorly specified that they blacken at normal volts.
Derek
Derek