Electric power is defined as the rate of doing work. Electric power refers to the rating of an electric device and is defined as the rate at which the device can transform electrical energy into other forms of energy such as mechanical energy , heat energy , and light energy. It is worth noting that resistance is the major circuit parameter that consumes electrical energy and dissipates it in terms of heat and light. The power loss in resistors is generally referred as ohmic loss or copper loss.

It is a variable loss and mainly depends on the load current. For a purely resistive circuit, the expression for power may be written as P = W/t = V²/R = I²R.

Another way, we can express as

P α V

and P α I

Where P (Work done per unit time) α VI ( Voltage X Current)

The volt is the potential difference across a conductor when passing a current of 1 A and dissipating energy at the rate of 1 W. It follows that,

P = VI

Symbol- W, Unit- watt

In simple load condition, V = IR.

So, Power will be

P = (IR) I = I² R = \(\frac{V^2}{R}\)