Which Metal Can Be Used As The Filament In An Electric Light Bulb?

The filament of an electric light bulb glows when it is heated. The filament must be made of metal because metals are the only good electrical conductors. Cost is not of great importance in selecting a metal for the job because the mass of metal needed is small. The color of light emitted depends on the temperature: at 2500 Celsius, white light is emitted. To heat the filament to this temperature, an electric current is passes through it. More heat is generated when an electric current passes through a thing wire than through a thick wire. A thin filament must be used.

The filament metal must fit this description:
•It must not melt or evaporate at 2500 Celsius.
•It must be able to withstand the thermal shock of being switched on an d off
•It must not break when it drawn into very fine wire: it must be ductile.
The only metal which combines the properties of high melting point (3410) and high ductility is tungsten. If tungsten came into contact with air at 2500 Celsius, it would burn. The filament is therefore enclosed in a glass bulb filled with a noble gas, usually argon due to it inert nature.

Aluminium

Titanium

Tungsten is used rather that copper, because it has stable properties between high ranges of temperature. ^^