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Question
Derive the relation between commercial unit of energy (kWh) and SI unit of energy (joule).
Solution
We can establish a relation between kilowatt-hour (kWh) and Joule (J) as –
1 kilowatt-hour = 1 kilowatt for 1 hour
= 1000 watt for 1 hour
But,
`1 "watt" = (1 "Joule")/(1 "s")`
So ,
1 kilowatt - hour = 1000 `"Joules"/"second"` for 1 hour
= `1000 "Joules"/"seconds" 60 xx 60 "seconds"`
= `3.6 xx 10^6` J
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