how bulb glows when electricity is passed through it.

explain the heating effect of electric current.

Heating Effect of Current

Electric current is actually the flow of electrons in the conducting material. Now, when these electrons flow, they encounter some resistance in the structure of the conductor, which accounts for the "resistance" of materials. As the electrons collide or vibrate, heat energy is generated depending on the resistance of the conductor. This overall effect is called heating effect of electrical current.

This what causes the bulb to glow as the tungsten filament, which as a very high resistance, heats up as current passes through it. This heating causes it to emit radiation which is interpreted as light.  

@Anumay... Good answers, keep it going!