NCERT · Class 10 · Science · ElectricityExplain the Joule's Law of Heating. Write its mathematical formula and mention two practical applications of this effect in daily life.

Joule's Law of Heating states that the heat produced in a resistor is directly proportional to the square of current ($I^2$) flowing through it, directly proportional to the resistance ($R$) of the given resistor, and directly proportional to the time ($t$) for which the current flows through the resistor. Mathematically, this is expressed as $H = I^2Rt$. This phenomenon occurs because when an electric current passes through a high-resistance conductor, the moving electrons collide continuously with the atoms and ions of the conductor, transferring their kinetic energy into heat energy. Two major practical applications of Joule's heating effect in everyday life include the electric iron, electric toaster, or room heater, where high-resistance heating elements convert electric energy into heat energy, and the electric fuse, which melts and breaks the circuit to protect appliances from excessive current.