Final answer:
The power expended as heat in electrical lines can be calculated using the average power formula, expressed in watts, which is joules per second. Kilowatt-hours is another energy unit used to represent energy consumption over time, with 1 kWh equating to 3.6 million joules. Option A is correct.
Step-by-step explanation:
The student is asking about the calculation of power expended as heat in electrical transmission lines, which is a physics concept concerning energy transfer and power dissipation. To solve this, we need to use the average power dissipation formula P_ave = I_{rms}^2 × R, where I_{rms} represents the root-mean-square of the current and R is the resistance of the electrical lines.
Using the provided values, we get P_ave = (500 A)^2 × (1.00 Ω) = 250 kW. It is important to note that the power expended as heat is different from the power delivered to customers.
When expressing the power expended as heat, we typically use the unit of watts (W), which is the SI unit for power and is equivalent to joules per second (J/s). The energy used in kilowatt-hours (kWh) can be calculated as E = P × t = (60 W) × (1000 h) = 60,000 W · h, showing the relationship between power and energy over time.
The choice between watts and kilowatt-hours for energy consumption depends on the context, with kilowatt-hours being more practical for measuring electrical energy consumed over time.
Ultimately, the energy units such as watts, joules, and kilowatt-hours provide different ways to express energy and power, depending on the application and the time factor involved in the energy transfer. The relationship between joules and kilowatt-hours is that 1 kWh = 3.6×10^6 J, indicating how these units relate for converting energy consumption figures.