Question

An electric oven of resistance $20\Omega$ draws a current of $10A$. It works $3hours$ daily. Calculate the monthly bill when energy costs $₹4perkWh$.

Answer 1

Step 1 - Given data

Resistance $R=20\Omega$

Current $I=10A$

Time for which the electric oven works daily $t=3h$

Step 2 - Finding the total time

Consider that the total for which the oven works in one month is $T$.

Time $T$ can be calculated as

$$\begin{gathered} T=30\times t \\ T=30\times 3h \\ T=90h \end{gathered}$$

Step 3 - Finding the power consumed by an electric motor

The power $P$ can be calculated as

$$\begin{gathered} P=I^2\times R \\ P={(10A)}^2\times (20\Omega ) \\ P=2000W \\ P=2kW \end{gathered}$$

(Note: $1000W=1kW$)

Step 4 - Finding the energy consumed by an electric motor

The energy $E$ can be calculated as

$$\begin{gathered} E=P\times t \\ E=(2kW)\times (90h) \\ E=180kWh \end{gathered}$$

Step 5 - Finding the monthly bill

Consider the total monthly bill is $R$ and the energy cost is $r$.

The total monthly bill $R$ can be calculated as

$$\begin{gathered} R=(180kWh)\times (₹4perkWh) \\ R=₹720 \end{gathered}$$

Final answer - Hence, the monthly bill is $₹720$.