why filament of bulb is made of tungsten?
Filaments in incandescent lightbulbs in particular need to:
- remain solid at high temperatures (2000 ~ 3500K)
- glow brightly when heated to the above temperatures through electric current
- can do the previous action many times before it fails
Tungsten is able to do those things listed above. Moreover, Tungsten has the highest melting temperature of all metals (and the second highest for an element).
In this application, tungsten has been shown to outlast other possible filaments, as well as glow brighter than the original carbon filament Edison used