What is the unit for the amount of energy used in 1 hour at a rate of 1 watt?

What is the unit for the amount of energy used in 1 hour at a rate of 1 watt?

• A. Joule
• B. Watt-hour
• C. Kilowatt-hour
• D. Calorie

Answer: (B)

Energy equals power times time, so a watt is one joule per second. For 1 hour at 1 watt, the energy is 1 J/s × 3600 s = 3600 joules. The unit that directly expresses energy produced or consumed at a constant power over a time interval is the watt-hour—1 watt for 1 hour equals 1 watt-hour (which is 3600 joules). Kilowatt-hours are 1000 watt-hours, and calories are a different energy unit not commonly used for this electrical context. So the correct unit is watt-hour.

Energy equals power times time, so a watt is one joule per second. For 1 hour at 1 watt, the energy is 1 J/s × 3600 s = 3600 joules. The unit that directly expresses energy produced or consumed at a constant power over a time interval is the watt-hour—1 watt for 1 hour equals 1 watt-hour (which is 3600 joules). Kilowatt-hours are 1000 watt-hours, and calories are a different energy unit not commonly used for this electrical context. So the correct unit is watt-hour.