How is one kilowatt hour (kWh) defined in energy terms?

One kilowatt hour (kWh) is defined as the amount of energy consumed when a power usage of one kilowatt is maintained for one hour. This means that if you have an electrical device that operates at a power level of one kilowatt and you run it continuously for one hour, it will have used one kilowatt hour of energy. This unit of measurement is commonly used in electricity billing and reflects the total energy consumed over time, allowing for an easy understanding of how energy is used in homes and businesses.

The other definitions provided do not accurately represent the concept of one kilowatt hour. For instance, power produced by one ampere in one minute does not relate to kilowatt hours since it does not consider the voltage aspect required to calculate power in kilowatts. Similarly, heat energy generated by a British Thermal Unit and energy consumed by an appliance over a day do not directly define the unit in question. The kWh specifically emphasizes the relationship between power and time, which is why option A is the correct answer.