One kilowatt hour is equal to

One kilowatt hour is equal to

36 × 10³ joule
36 × 10⁵ joule
10³ joule
10⁵ joule
This question was previously asked in
UPSC NDA-2 – 2016
One kilowatt hour (kWh) is a unit of energy. It is the energy consumed by a 1 kilowatt (kW) power device operating for 1 hour (h).
1 kilowatt (kW) = 1000 watts (W) = 1000 joules per second (J/s).
1 hour (h) = 60 minutes × 60 seconds = 3600 seconds (s).
Therefore, 1 kWh = 1 kW × 1 h = (1000 J/s) × (3600 s) = 3,600,000 J.
In scientific notation, this is $3.6 \times 10^6$ J, which is equal to $36 \times 10^5$ J.