Electric power is defined as the amount of work done by an electric current, or the rate at which electrical energy is transferred, which the International System of Units or the SI unit measures in Watts. The term wattage colloquially means electric power in watts.
According to British physicist James Joule, electrical and mechanical energy are interchangeable. In direct current resistive circuits, Joule's Law calculates instantaneous electrical power.
Energy storage elements such as inductors and capacitors cause periodic reversals of energy flow in alternating current. Real power, reactive power, and complex power, are terms used by engineers to describe energy flow in a system.
Electrical power distribution widely takes place via cables and electricity pylons. Work gets done when electric current flows in a circuit with resistance. Heat devices such as electric heaters, light devices such as light bulbs, motion devices such as electric motors, and sound devices such as loudspeakers, convert and adapt this work usefully.
The electrical power industry viewed as a public utility produces and delivers electrical power or electrical energy through grids. The four processes involved in the electrical power industry are, electricity generation (power stations), electric power transmission, electricity distribution, and electricity retailing. Though heavily regulated, some companies own the entire infrastructure from generating stations to transmission and distribution. In deregulated areas, users may opt for the green electricity.