Define kilowatt hour and power.

(N/A) $1$. Power: Power is defined as the rate at which work is done or the rate at which energy is transferred. Mathematically, $P = \frac{W}{t}$, where $W$ is the work done and $t$ is the time taken. The $SI$ unit of power is the watt $(W)$, where $1 \ W = 1 \ J/s$.
$2$. Kilowatt hour $(kWh)$: $A$ kilowatt hour is a unit of energy. It is defined as the amount of energy consumed by an electrical device of power $1 \ kW$ operating for $1 \ hour$.
$1 \ kWh = 1000 \ W \times 3600 \ s = 3.6 \times 10^6 \ J$.