# Underhung incandescent lamps and the effects of gravity and magnitism on them



## ship (May 22, 2010)

Looking up at a under hung incandescent 300w lamp. Two questions come to mind are not easy perhaps in asking as a challenge an answer to.

Assuming an incandescent lamp without the halogen effect, are those spent particles of tungsten magnetic? Could a washer like magnet around the neck of the say PS-35 lamp, if applied be effective in collecting the spent tungsten particles from the filament?

After that another question of if gravity has an effect within such a lamp by way of spent tungsten particles. Do they fall to the bottom or to the sides of the globe and or all about it and why?


----------



## zmb (May 22, 2010)

I'm not sure if the tungsten would be magnetic and work with the washer to collect.

However, it makes most sense that spent tungsten would evaporate to the top of the bulb due to the fact that hot rises, cold sinks. A bathroom globe lamp in my house has most of the tungsten on the top of the bulb and a little bit every where else.


----------



## WooferHound (Jul 6, 2010)

Another thing is that magnets lose the magnetic effect if the temperature goes over the curie temperature which is possible in an incandescent lamp.
Curie temperature - Wikipedia, the free encyclopedia


----------



## ship (Jul 6, 2010)

So given heat rises and that's where tungsten particles, why do some base up espcially metal halide lamps (in this case from the electrodes) as used for normal overhead lighting applications bother with a reflector assembly mounted at the neck of the globe? Also, wouldn't the now cool tungsten particles rather fall with gravity to the bottom of the lamp than deposit themselves on the neck of the underhung lamp neck if true? I also note some silicone sand in early DKZ lamps as used to swirl away the spent tungsten particles on the globe of the lamp. What's that do to the theory?


----------



## zmb (Jul 7, 2010)

I would think the silicone sand would act as a mild abrasive to remove the tungsten from the bulb.


----------

