Which pairing of units correctly describes electrical energy and power?

• A. kilowatt-hours, watts
• B. amps, kilowatt-hours
• C. volts, amps
• D. watts, amps

Answer: (A)

Energy is the total amount of electrical work used over time, while power is the rate at which that energy is used. Because energy describes quantity over a duration and power describes how fast energy is transferred, their natural units are kilowatt-hours for energy and watts for power.

That’s why the correct pairing is energy in kilowatt-hours and power in watts. For example, a 1000-watt device operating for one hour consumes 1 kilowatt-hour of energy.

The other options mix concepts that aren’t energy or power: amps measures current, volts measures potential difference, and pairing current or voltage with energy or pairing energy with current doesn’t directly describe both energy and power. Watts paired with amps describes power and current, but it doesn’t specify energy, which is what the question seeks.