Q8DQ - University Physics with Modern Physics

Question

Fractured Physics. People often call their electric bill a power bill, yet the quantity on which the bill is based is expressed in kilowatt-hours. What are people really being billed for?

Step-by-Step Solution

Answer

The people are really paid for the electric bill.

Step 1: Concept/Significance of power

The power is generally expressed in or more commonly as watts. The power is the change in work over a given time interval.

$$\begin{gathered} \mathit{P}\mathbf{=}\underset{\mathbf{∆}\mathbf{t}\mathbf{\to }\mathbf{0}}{\mathbf{l}\mathbf{i}\mathbf{m}}\frac{\mathbf{∆}\mathbf{W}}{\mathbf{∆}\mathbf{t}} \\ \mathbf{=}\frac{\mathbf{d}\mathbf{W}}{\mathbf{d}\mathbf{t}} \end{gathered}$$

Step 2: Find what people are being billed for

The electricity bill is calculated with and this is the unit of energy. A kilowatt-hour is equal to the energy provided by $1000 \text{watts}$ in one hour.

$$\begin{gathered} 1 \text{kWh}=1\left({10}^3 \text{W}\right)\left(\text{hour}\right) \\ ={10}^3\left(\frac{\text{J}}{\text{s}}\right)\left(3600 \text{s}\right) \\ =3.6\times {10}^6 \text{J} \end{gathered}$$

 

The electricity bill is prepared based on the number of kilowatt-hours consumed. Kilowatt-hour is a unit of electrical energy which means the electricity bill is prepared on the consumption of electrical energy. Therefore, the bill is really called an electric bill rather than a power bill.

 

Hence, the people are paid for the electric bill.