Electrical Energy and Power

The basic unit of energy is a Joule (J), which is equal to one watt of power expended for one second. In the day-to-day scenarios such as household electricity consumption, joule is too small a unit to be convenient. For billing and metering purpose, it is measured in kilowatt-hours (kWh). Electrical energy is measured in kilowatt-hours (kWh) as the commercial unit. 1kWh = 1000 W * 3600 s 

For calculating the units consumed, we will be using the following formula 

Units = [Power (W) x Time (h)]/1000

The SI unit of the electrical power is Watt which is symbolized as W. One watt is equal to one joule per second (J/s). In the context of current and voltage, one watt is the power consumed when one ampere of the current flows through the potential difference of one volt.