(a) Electric power of an electrical device is the rate at which it consumes electrical energy.
$$P = \frac{W}{t} = VI$$
SI unit: Watt (W).
(b) Given: Power P = 2 kW, Time t = 2 h
(i) Energy in kilowatt hour:
$$E = P \times t = 2 \text{ kW} \times 2 \text{ h} = \textbf{4 kWh}$$
(ii) Energy in joules:
$$1 \text{ kWh} = 3.6 \times 10^6 \text{ J}$$
$$E = 4 \times 3.6 \times 10^6 = \textbf{1.44 \times 10^7 \text{ J}}$$
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