Power Dissipation in Resistance

1. While current flows through a resistance, heat is generated due to friction among the moving free electrons and the atoms which block the path of electron flow.
2. The heat is evidence that power is utilized in generating current.
3. The electric energy which converted to heat is considered to be used up or dissipated due to the reason calories of work cannot be returned to the circuit like electric energy.
4. Since in the resistance power is dissipated of a circuit, it is suitable to express the power in terms of resistance R.
5. The formula P=V x I may be arranged as follows.

                       Through Substituting   IR for V,

                                                            P =V x I

                                                                =IR x I

                                                                 =I²R

It is the common form of the formula because of heat generated in a resistance because of current R.

For another form

            Through substituting V/R for I

                                                                 P= V x I

                                                                = V x V/R

                                                                 = V²/R

             In all of the formulae, V is the voltage across R in ohms generating the current in amperes for power in Watts.