The commercial unit of electrical energy is kilowatt-hour (kWh), which

The commercial unit of electrical energy is kilowatt-hour (kWh), which is equal to

$3.6 imes 10^6$ J
$3.6 imes 10^3$ J
$10^3$ J
1 J
This question was previously asked in
UPSC NDA-2 – 2022
The commercial unit of electrical energy is kilowatt-hour (kWh). Energy consumed is calculated as Power multiplied by Time.
1 kilowatt (kW) = 1000 Watts (W)
1 hour (h) = 3600 seconds (s)
Energy (Joules) = Power (Watts) × Time (seconds)
1 kWh = 1 kW × 1 h = 1000 W × 3600 s = 3,600,000 Joules (J)
In scientific notation, this is $3.6 \times 10^6$ J.
1 kWh is the energy used by a 1 kW device operating for 1 hour. The conversion factor from kilowatt-hour to Joules is obtained by converting kilowatts to watts and hours to seconds.
The Joule is the SI unit of energy, but for practical purposes, especially for calculating electricity consumption in households and industries, kilowatt-hour is commonly used. It represents a larger unit of energy. 1 unit of electricity on a meter typically corresponds to 1 kWh.