Question

Express watt-hours in terms of joules.

Answer 1

1. Joule is the SI unit of electrical energy.
2. Watt-hour is also a unit of electrical energy.
3. Watt is a unit of power, $1watt=\raisebox{1ex}{$joule$}\!\left/ \!\raisebox{-1ex}{$second$}\right.$.
4. $$\begin{gathered} 1Watt-hour=\raisebox{1ex}{$joule$}\!\left/ \!\raisebox{-1ex}{$second$}\right.\times 1hour \\ 1Watt-hour=\raisebox{1ex}{$joule$}\!\left/ \!\raisebox{-1ex}{$second$}\right.\times 3600second=3600joule \end{gathered}$$
5. Hence, $1watt-hour=3600joule$.