Household Electricity — Question 8

We pay the cost of our electricity bill in unit kWh (kilowatt hour).

Since,

$\text{Power} = \dfrac{\text{Energy}}{\text{Time}} \\[1em] \therefore \text{Energy} = \text{Power} \times \text{Time} \\[1em] \text{i.e. } \text{Energy (in kWh)} \\[1em] = \text{Power (in kWh)} \times \text{Time (in h)}$

Hence,

1 kWh = 1 kW x 1 h

= 1000 W x (60 x 60 s)

= 36,00,000 J

= 3.6 x 10⁶ J

So 1 kWh = 3.6 x 10⁶ J.