What is the value of 1 kilowatt-hour in joules?

• A. 3.6 × 10^6 J
• B. 3.6 × 10^3 J
• C. 3.6 × 10^9 J
• D. 3.6 J

Answer: (A)

The main idea is that energy in joules comes from multiplying power by time: energy = power × time. A kilowatt-hour is the energy used when a device of power 1 kilowatt runs for 1 hour.

Convert to SI units: 1 kilowatt = 1000 joules per second, and 1 hour = 3600 seconds. So the energy is 1000 J/s × 3600 s = 3.6 × 10^6 J.

Thus, 1 kilowatt-hour equals 3.6 × 10^6 joules. (The other numbers would correspond to different times or larger scales, not 1 kWh.)