Why is a Tungsten filament used in incandescent bulbs? (Factual Question)

1. Jan 14, 2010

SankalpSethi

1. The problem statement, all variables and given/known data
Why is a tungsten filament used in incandescent bulbs?

I earlier thought that it was due to the high resistivity of tungsten , but i was wrong , the resistivity of tungsten is low at 5.2 * 10^-8 Is it due to its high melting point?? I cant figure out as high melting point doesnt seem to be the only reason for selection of Tungsten.
Thank You

2. Jan 14, 2010

mgb_phys

What physical properties do you want from a lamp filament ?
hint - What does Tungsten have the highest of ?

3. Jan 14, 2010

SankalpSethi

i think it should be high melting point ( Tungsten has a MP of 3380 C) but again , it has a very low resistivity which means it has a low resistance. So according to Joule's law of heating , a very less amount of heat would be produced . What are your views on this?

4. Jan 14, 2010

mgb_phys

You want less heat - it's wasted energy but that's a secondary point.

The important point is that to get visible light you need the filament to be as hot as possible, an the lamp will fail when the filament melts - so you need the highest melting point material possible (that is also a conductor of course)

5. Jan 14, 2010

SankalpSethi

I get it , so the main reason is melting point! Thanks a ton , i have an exam tommorow , this will surely help!