A 60 W bulb runs for 1 hour. How much energy does it use?

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Multiple Choice

A 60 W bulb runs for 1 hour. How much energy does it use?

Energy used equals power times time. A 60 W bulb delivers 60 joules each second. In one hour there are 3600 seconds, so the energy is 60 × 3600 = 216,000 J, which is 216 kJ. You can also see this as 0.06 kW for 1 hour, giving 0.06 kWh, and since 1 kWh = 3.6 MJ, that's 0.06 × 3.6 MJ = 0.216 MJ = 216 kJ.

Energy used equals power times time. A 60 W bulb delivers 60 joules each second. In one hour there are 3600 seconds, so the energy is 60 × 3600 = 216,000 J, which is 216 kJ. You can also see this as 0.06 kW for 1 hour, giving 0.06 kWh, and since 1 kWh = 3.6 MJ, that's 0.06 × 3.6 MJ = 0.216 MJ = 216 kJ.

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