The electric energy consumed in a circuit is defined as the total work done in maintaining the current in an electric circuit for a given time.
Electric Energy =VIt=I2Rt= V2/Rt=P.t
SI unit is Joule, also 1 joule = watt-second
Commercial unit of electric energy is kilowatt hour (kWh) or Board of trade unit (B.O.T.U) or UNIT of electricity
1kWh=1000watt x 1 hours = 1000watt x 60min x 60s=3.6x106 J
No. of units of electricity consumed = watt-hour/1000