Question

why is tungsten filament in an electric bulb made thin and coiled?

Answer 1

tungsten is an element whose melting point is high...it can withstand with large temperature and starts glowing...Other elements like iron or copper gets melt if heated at the same temperarure...

We know that Resistance is a property of a material which opposes the flow of current in a conductor...

And following are the factors which affects the resistance :
=> Length of a conductor
=> Area of a cross swction
=> Nature of material
=> Temperature

Resistance is directly proportional to the length of a conductor and inversely proportional to the area of cross section...

Tungsten coil is thin as its area of cross section is smaller so resistance in a coil is larger...And it is coiled to increase the length of the conductor...All these constructions of a coil increases the resistances of the coil which increases the Heat as
H ( Heat ) = I ( Square ) R t
=> Heat is directly proportional to the resistance as per Joule's law...
=> More heat , so it glows without melting

This is the reason why tugsten is used as a filament in bulbs...

Answer 2

So when bulb gets fuse it breaks