Final answer:
A watt and a kilowatt are units of power, and a kilowatt-hour is a unit of energy. The kilowatt-hour is the product of power in kilowatts and time in hours, equating to 3.6 million joules. This unit is commonly used on electric bills due to its convenience for measuring typical household energy use.
Step-by-step explanation:
Between a watt (watt), a kilowatt (kilowatt), and a kilowatt-hour (kilowatt-hour), the watt and kilowatt are units of power, while the kilowatt-hour is a unit of energy. A watt is defined as one joule of energy per second, making the kilowatt simply one thousand watts. The kilowatt-hour is the energy expended by a power consumption rate of one kilowatt over the period of one hour, which results in using energy, and it's equivalent to 3.6 x 106 joules.
Understanding the difference between these units is important because it reflects the rate at which energy is used versus the total amount of energy used. Kilowatts is a measure of how fast energy is being used, similar to how a speedometer measures speed. In contrast, kilowatt-hours reflect the total amount of energy used, similar to how an odometer measures the total distance traveled.
The energy unit on electric bills is the kilowatt-hour because it is convenient for accounting for typical household electrical power consumption, which occurs at the kilowatt level over extended periods. Energy consumption is often listed in kilowatt-hours on electricity bills instead of joules because it's a more practical measure for the scale at which electricity is used in residential settings.