The heating effect of current is defined by Joules law of heating. It is also called ohmic heating and resistive heating. In a conductor when an electric field is applied across its ends, the free electrons available in it start drifting opposite to the direction of the electric field. These electrons collide with the atoms which have lost the electrons. As a result of these collisions, some energy of the electrons is transferred to the atoms which vibrate violently as they gain energy. Thus, heat is developed in the conductor. Greater the current, greater will be the rate of collision and so greater will be the heat produced.
Joule's heating effect
According to Joule's law of heating, the heat produced in a wire is directly proportional to
(1) Square of current (I2)
(2) Resistance of wire (R)
(3) Time (t), for which current is passed.
i.e., Heat producted, H = I2 R t Joules.
Applications of Joule's heating effect in daily life :
(1) The heating effect of current is utilised in the working of electric heating appliances such as electric iron, electric kettle, electric toaster, electric oven, room heaters, geysers, etc.
(2) The heating effect of electric current is utilised in electric bulbs.
(3) The heating effect of electric current is utilised in electric fuse for protecting household wiring and electrical appliances.
(4) The heating effect of electric current is utilised in laundry iron.
