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The unit 'watt' is very small. Therefore, in actual practice we use a much
larger unit called 'kilowatt'. It is equal to 1000 watts. Since electrical
energy is the product of power and time, watt hour (W h) can also be
considered as unit of electric energy.
One watt hour is the energy consumed when 1 watt of power is used for 1 hour. The commercial unit of electric energy is kilowatt hour (kW h), commonly known as 'unit'.
1 kWh is defined as the amount of
electrical energy consumed in 1 hour when the rate of consumption is
1000Joules/second
1 kW h = 1000 watt x 3600 second
= 3.6 x 106 watt second
= 3.6 x 106 J
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