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## 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

1. What is heating effect of electric current?

2. Derive the formula for heating effect of electric current.

3. What are applications of heating effect of electric current?

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