ABSTRACT
The authors start by considering how the power varies over a complete cycle of the supply in the case of a pure resistive load and then move on to see what happens when a load is reactive rather than resistive. In circuits that contain only inductance or capacitance, power is taken from the supply on each cycle when the magnetic or electric fields are created and then returned to the supply when the fields later collapse. Power factor provides us with an indication of how much of the power supplied to an alternating current (AC) circuit is converted into useful energy. They introduces the concepts of power and power factor in an AC circuit. When an AC load only has resistance, the voltage and current in the load will be in phase and all of the applied power will be dissipated as heat in the resistor. Most AC loads have both resistance and reactance.
