If a device rated at 2 kW runs for 1.5 hours, how many kWh are used?

If a device rated at 2 kW runs for 1.5 hours, how many kWh are used?

• A. 2.0 kWh
• B. 2.5 kWh
• C. 3.0 kWh
• D. 3.5 kWh

Answer: (C)

Energy used equals power times time. A 2 kW device running for 1.5 hours uses 2 kW × 1.5 h = 3.0 kWh. A kilowatt-hour is the amount of energy used when a 1 kW device runs for 1 hour, so doubling the power for one and a half hours gives 3 kWh. The other options would require different times or powers.

Energy used equals power times time. A 2 kW device running for 1.5 hours uses 2 kW × 1.5 h = 3.0 kWh. A kilowatt-hour is the amount of energy used when a 1 kW device runs for 1 hour, so doubling the power for one and a half hours gives 3 kWh. The other options would require different times or powers.