State joule's law of heating.

If the electric circuit is purely resistive, the source energy continually get dissipated in the form of heat.this is known as Joule's law of heating .

The law implies that heat produced in a resistance is 1- directly proportional to square of current for a Given resistance. 2- directly proportional to resistance for a given current flow through the resistor

Joule’s Law of Heating
The heat that is generated because of the current flow in an electric wire is described in Joules. The mathematical expression of Joule’s law is as explained below.

Joule’s first law
The joule’s first law shows the relationship between heat produced by a flowing electric current through a conductor.

Q = I2 R T

Where,

Q indicates amount of heat,

I shows electric current

R is the amount of electric resistance in conductor

T denotes time

The amount of generated heat is proportional to wire’s electrical resistance when the current in the circuit and the flow of current is not changed.
The amount of generated heat in conductor carrying current is proportional to square of the current flow through the circuit, when the electrical resistance and current supply is constant.
The amount of heat produced because of the current flow is proportional to the time of flow, when the resistance and current flow is kept constant.

When current I flow through a resistor of electric resistance R, heat is produced. The heat produced H depends directly on the square of the current, resistance and time t for which the current is allowed to pass. H=I²Rt, Is called Joule's law of heating