Heating Effect of Electric Current

When an electric current is passed through a conductor, the conductor becomes hot after some time and produces heat. This happens due to the conversion of some amount of electric energy, passing through the conductor, into heat energy. This effect of electric current is calledheating effect of electric current.

The heating effect of electric current depends on three factors:

The resistance,Rof the conductor. A higher resistance produces more heat

The time,tfor which current flows. The longer the time the larger the amount of heat produced

The amount of current,I. the higher the current the larger the amount of heat generated

Heating effect of electric current I, through a conductor of resistance, R for a time, t is given byH = I2Rt. This equation is called theJoule’s equation of electrical heating. It quantifies the heating effect of electric current.

Derivation: Joule’s Equation of Electric Heating

To calculate the heat produced in a conductor, consider current I is flowing through a conductor AB of resistance R for time t. also consider that the potential difference applied across its two ends is V.

Now, total amount of work done in moving a charge q from point A to B is given by:

W = q X V--------(1)

Now, we know thatcharge = current × time

or q = I X t

and V = I X R(Ohm’s law)

Putting the values of q and V in equation (1), we get

W = (I X t) X (I X R)

Or W = I2Rt

Now, assuming that all the work done is converted into heat energy we can replace symbol of‘work done’with that of‘heat produced’. So,

H = I2RT