Joule showed the heating effect due to the resistence of wire which cary the current.

yes,joule is a heating reversible effect .

The joule

Heating pads contain heating elements that convert electricity to heat by passing current through a conductor (usually a wire). This process is variously referred to as resistive heating, ohmic heating, or Joule heating. The amount of heat generated is proportional to the square of the applied current multiplied by the resistance of the conductor. If SI units are employed (amperes for current and ohms for resistance) the unit of heat energyis called a joule.

State and derive joul's law of heating effect of an electric current.