Asked in PhysicsChemistry
Why is tungsten used as a filament in lamps?
March 04, 2018 8:05AM
it is used bcoz it has a high melting point and thus it does not
melt in lamps...
Tungsten is used in filaments because it is lightweight and can conduct heat very quickly. It can also attain very high temperatures without melting.
Tungsten is used because it has a high melting point and retains its strength in temperature extremes.
Tungsten-based alloys are used because tungsten has the highest melting point and the lowest thermal expansion coefficient of any metal. Both these properties are very useful for a light bulb filament.
A low melting point would mean the bulb couldn't be operated at high temperatures, and the light would be yellowish or reddish.
A high thermal expansion coefficient would mean that the length of the filament would change a lot when it was heated; this would cause mechanical problems as the filament expanded and contracted with use.
Experiments were made with different materials to use as the
filament, including natural fibres, pure metals and alloys of
different metals, to find the material which had the longest life
whilst glowing brightly enough to give out visible light. The metal
Tungsten was found to be the best, because of its high melting
point (almost 3700 K) and good resistance to electrical
as it has a high melting point and retains its strength in temperature extremes .
Being a metal it will conduct electricity and because it has the highest melting point of all the non-alloyed metals (and the second highest of all the elements after carbon) and thus will not melt at the point at which it is incandescent.
the only metal that will light up in the whole world is the tungsten so they uses the tungsten for the light bulb filaments.
/ because of the high melting point
Because Tungsten has a very high heat of fusion where it would take great energy to change from one phase to another. In this case, solid to liquid, thus it will remain solid as long as its heat of fusion is below its maximum heat of fusion. Additionally, Tungsten has a superb tensile strength that allow it to overcome extreme stress.
high atomic number high melting point
Tungsten has a very high melting and boiling point infact it has the highest and so therefore it wont easily melt.
It stays together much longer than the carbon filament Edison used. That wire gets very hot.
The metal tungsten is used for the filaments in incandescent bulbs. It has a high melting point and retains its strength when heated. The tungsten's resistance makes it glow white-hot, and inert gases (mostly nitrogen) in the bulbs keep the tungsten from oxidizing.