Question

An electric heater of 1000 watt is used for 2 hours a day, what is the cost of using it for a month of 28 days. If 1 unit cost Rs 3.00?

Answer 1

Dear Student,

$$\begin{gathered} \mathrm{Power},\mathrm{P}=1000\mathrm{W}=1\mathrm{kW} \\ \mathrm{time},\mathrm{t}=2\mathrm{hour} \\ \mathrm{Energy}\mathrm{used}\mathrm{in}\mathrm{a}\mathrm{day},\mathrm{E}=\mathrm{P}\times \mathrm{t} \\ \mathrm{E}=1\times 2=2\mathrm{kWh} \\ \mathrm{Energy}\mathrm{used}\mathrm{in}\mathrm{a}\mathrm{month},\mathrm{E}=2\times 28=56\mathrm{kWh} \\ \mathrm{or},\mathrm{E}=56\mathrm{units} \\ 1\mathrm{unit}=\mathrm{Rs}3 \\ 56\mathrm{units}=3\times 56=\mathrm{Rs}168 \end{gathered}$$