If a 2 kW device runs for 1.5 hours, what is the energy in kWh?

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Study for the IGCSE Physics Electricity. Study with flashcards and multiple choice questions, each question has hints and explanations. Get ready for your exam!

Multiple Choice

If a 2 kW device runs for 1.5 hours, what is the energy in kWh?

Explanation:
Energy equals power times time. When power is in kilowatts and time in hours, the energy comes out in kilowatt-hours. So a 2 kW device running for 1.5 hours uses 2 × 1.5 = 3 kWh. This also fits the intuition: a 1 kW device would use 1 kWh in 1 hour, and here the time is longer and the power is double, giving 3 kWh overall. (For reference, 3 kWh is 10.8 MJ, since 1 kWh = 3.6 MJ.)

Energy equals power times time. When power is in kilowatts and time in hours, the energy comes out in kilowatt-hours. So a 2 kW device running for 1.5 hours uses 2 × 1.5 = 3 kWh. This also fits the intuition: a 1 kW device would use 1 kWh in 1 hour, and here the time is longer and the power is double, giving 3 kWh overall. (For reference, 3 kWh is 10.8 MJ, since 1 kWh = 3.6 MJ.)

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