Question:
What is the commercial unit of electrical energy ? Represent it in terms of joule.
Solution:
kilowatt hour (kWh) is the commercial unit of electrical energy.
$1 \mathrm{kWh}=1000 \mathrm{Watt} \times 3600 \mathrm{~s}$
$=3.6 \times 10^{6} \frac{\mathrm{J}}{\mathrm{s}} \times \mathrm{s}$
$=3.6 \times 10^{6} \mathrm{~J}(\because 1 \mathrm{Watt}=1 \mathrm{~J} / \mathrm{s})$