Electrical energy Equations
The amount of electric energy transferred to an appliance depends on its power and the length of time it is switched on. The amount of mains electric energy transferred is measured in kilowatthours, kWh. One unit is 1 kWh.
E = P × t

E is the energy transferred in kilowatthours, kWh

P is the power in kilowatts, kW

T is the time in hours, h.
Note that power is measured in kilowatts here instead of the more usual watts. To convert from W to kW you must divide by 1,000.
For example, 1,000 W = 1,000 ÷ 1,000 = 1 kW.
Also note that time is measured in hours here, instead of the more usual seconds. To convert from seconds to hours you must divide by 3,600.
For example, 7,200 s = 7,200 ÷ 3,600 = 2 h.

