What is the heating effect of electric current? Find the expression for calculating heat?

Hint: When electric current is supplied to a purely resistive conductor, the energy of the electric current is dissipated entirely in the form of heat and because of that the resistor gets heated. This heating of resistor is because of dissipation of electrical energy and this effect is know was Heating effect of Electric current

Complete step by step solution
Let us consider a conductor AB of resistance R having a potential difference V through which current I is flowing.
So if you want to move a charge q from point A to point B the amount of work done is given by
 $ W = q \times v $
Where W is the work done, Q is the charge and , V is the potential difference.
 $ \Rightarrow q = i \times R $
Where I is current flowing through the conductor and R is the resistance.
 $ \Rightarrow V = I \times R $ (ohm's law)
Now we will substitute the values of q and v in the formula for work done which gives us
 $ \Rightarrow W = \left( {I \times t} \right) \times \left( {I \times R} \right) $
 $ \Rightarrow W = {I^2}Rt $
Here we are assuming that all the work that is done is converted into heat energy. Therefore
 $ H = {I^2}Rt $ .

Additional information
Heating effect of electric current depends on three factors. Resistance of the conductor, the time duration for which current flows and the amount of current produced. As you can see from the above equation that heat produced is directly proportional to these three factors.
This equation is also called the Joules equation of electrical heating.

Note
Some of the household electrical appliances convert electrical energy into heat by this means. This includes filament lamps, fluorescent lamps, electric cookers, electric kettles etc.Resistance of the conductor, the time duration for which current flows and the amount of current produced.