Question

State joule’s law of heating

Answer 1

Hint: When an electric current is passed through a high resistance wire, then the resistance wire becomes very hot and produces heat. This is called the heating effect of current.
The joule’s law of heating gives the expression for heat which is produced in wire due to current flow

Complete step by step answer:
Basically, joule heating is nothing but a resistance of ohmic heating and also called a process by which the passage of an electric current through a conductor produces heat.
According to Joule’s law of heating, when an electric current is passed through a high resistance wire, then heat will be produced and the heat produced in a wire is directly proportional to -
(i) square of current $({I^2})$
 $H \propto {I^2}$ …..(1)
(ii) Resistance of wire $(R)$
$H \propto R$ …..(2)
(iii) The time $(t)$ for which current flows
$H \propto t$ …..(3)
Now combination equation 1, 2 & 3
$H \propto {I^2}Rt$
$H = {I^2}Rt$
Above expression represents the heat produced in the wire.
This is known as Joule’s law of heating.

Note:
Practical application of heating effect of current
1. Electric from
2. Incandescent lamp
3. Electric fuse
4. Electric quen
5. Electric heater