Question

Why the filament of bulb has high melting point?

Answer 1

A filament is made up of a substance having high melting point(like tungsten) because A bulb lights up by heating the filament. The heated filament is the source of light,and if the melting point of filament's substance is low,it may melt. Thus,element for filament is choosen wisely(like Tungstens having M.P of about 3500 degree celsius. Also,bulb is filled with a noble gas or a very less reactive gas(like nitrogen,argon) so that the heated element should not react with it.