Question

Why does an electric bulb glows when current passes through it?

Answer 1

◆There is an tungsten wire,generally called the filament ,present in the bulb.
◆It's resistivity is quite high .
◆Hence applying Joule's heating effect(formula),a considerable amount of heat is generated.
◆The various inert gas present in the bulb have a characteristic property of emitting different type of colour of light .
◆Hence current passing through the wire make the tungsten wire to become red hot and inert gas absorb that heat emitting light.