Electricity - Heating effect of electric current

The heating effect of electric current occurs when an electric current passes through a conductor of high resistance, causing it to become hot and produce heat. This involves the conversion of electrical energy into thermal energy.

According to Joule's Law of Heating, the heat ($H$) produced in a resistor is: (1) directly proportional to the square of current ($I^2$) for a given resistance, (2) directly proportional to the resistance ($R$) for a given current, and (3) directly proportional to the time ($t$) for which the current flows through the resistor.

Practical applications of the heating effect include domestic appliances like electric irons, toasters, ovens, and heaters which use alloys like Nichrome due to their high resistivity and high melting point.

In an electric bulb, the heating effect is used to produce light. The filament is usually made of Tungsten because it has a very high melting point of $3380^{\circ}C$ and does not oxidize easily at high temperatures.

An electric fuse is a safety device based on the heating effect of current. It consists of a piece of wire made of an alloy with a low melting point. If the current exceeds a safe limit, the fuse wire melts and breaks the circuit.

Electric Power ($P$) is the rate at which electrical energy is consumed in a circuit. Its SI unit is the Watt ($W$).