If Problem 21 had resulted in \(5,000 \mathrm{~W},{ }^{46}\) how many kilowatt- hours (kWh) are expended in a 24 -hour period? At an electricity cost of around \(\$ 0.15\) per \(\mathrm{kWh},{ }^{47}\) about how much will it cost, per day, to maintain heat?

The kilowatt-hour is a unit of energy commonly used to measure electricity usage. It represents the amount of energy consumed when a 1,000-watt appliance, such as an electric heater, is used for one hour. For instance, if a light bulb rated at 100 watts is left on for 10 hours, it uses one kilowatt-hour of energy (100 watts x 10 hours = 1,000 watt-hours, or 1 kWh). This unit is key when calculating power consumption and energy costs, as utility companies typically charge for electricity by the kilowatt-hour.

Understanding this unit of measurement is essential when analyzing electricity usage or attempting to optimize energy expenditure, whether it be in a home or business setting.

Energy cost calculation is determining the total cost of energy consumed over a specific period. To do this, multiply the total energy consumed, measured in kilowatt-hours (kWh), by the cost per kilowatt-hour as set by the energy provider. This calculation helps consumers understand their energy bills and provides an incentive to reduce power consumption to save on costs. By being aware of the per-unit cost of electricity, consumers can also make more informed decisions about their energy usage, which can result in more efficient energy consumption patterns and financial savings over time.

Example Calculation

For instance, using the solution from the exercise, at a rate of \(0.15 per kWh, the cost for consuming 120 kWh over 24 hours is calculated as follows: Cost = 120 kWh x \)0.15/kWh = $18 per day.

Electricity usage refers to the amount of electrical power consumed by all the electrical appliances and devices within a certain period, usually expressed in kilowatt-hours. Tracking electricity usage is fundamental for both residential and commercial energy consumers, as it forms the basis for electricity billing and can help identify ways to optimize energy use and reduce costs. By understanding which devices consume the most power and when peak usage occurs, individuals and businesses can take strategic actions such as upgrading to energy-efficient appliances, using timers, or adjusting usage patterns to more cost-effective times of the day.

Monitoring and managing electricity usage is also a crucial step towards achieving better energy efficiency and sustainability goals. Implementing energy-saving practices can significantly reduce environmental impact and help create a more sustainable future.

Power to energy conversion is the process of calculating the total energy used, given the power rating of an appliance and the length of time it's been in operation. Power, measured in watts (W) or kilowatts (kW), indicates the rate at which an appliance consumes energy. Energy, on the other hand, reflects the total consumption over time and is measured in kilowatt-hours (kWh).

To convert power (in kW) to energy (in kWh), multiply the power by the number of hours of usage. For example, in the textbook solution, a 5,000-watt (or 5 kW) heater running for 24 hours uses 5 kW x 24 hours = 120 kWh of energy. This process is fundamental when planning energy budgets, understanding billing, and managing energy use in daily life. Users can calculate the potential cost of running a new appliance or assess the energy efficiency of their current usage patterns and make adjustments accordingly.