HEATING EFFECT OF ELECTRIC CURRENT
When an electric current is passed through a conductor, the conductor becomes hot after some time and produce heat. This happens due to the conversion of some electric energy passing through the conductor into heat energy. This effect of electric current is called heating effect of current.
The heating effect of current was studied experimentally by Joule in 1941. After doing his experiments Joule came to the conclusion that the heat produced in a conductor is directly proportional to the product of square of current (I2), resistance of the conductor (R) and the time (t) for which current is passed. Thus,
H 
I2Rt
Derivation of Formula
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 that charge = 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
Applications of Heating Effect of Current
The heating effect of current is used in various electrical heating appliances such as electric bulb, electric iron, room heaters, geysers, electric fuse etc.
Examples of Heating Effect of Electric Current
Test your understanding by answering the following questions:
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- What is heating effect of an electric current?
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- Derive the formula for heating effect of an electric current.
- What are applications of heating effect of an electric current?
