Which captured the greatest amount of energy?

Which captured the greatest amount of energy?

• A. a 40-watt fluorescent lamp used for 8 hours
• B. a 60-watt electric fan used for 6 hours
• C. a 100-watt LCD TV used for 4 hours
• D. a 20-watt incandescent bulb used for 24 hours

Answer: (D)

Energy is what you get when you multiply power by the time the device runs. In practical terms, that’s power in watts times hours, which you can think of as watt-hours (or kilowatt-hours when you divide by 1000). Compute each scenario: - 40 W for 8 h: 40 × 8 = 320 Wh (0.32 kWh) - 60 W for 6 h: 60 × 6 = 360 Wh (0.36 kWh) - 100 W for 4 h: 100 × 4 = 400 Wh (0.40 kWh) - 20 W for 24 h: 20 × 24 = 480 Wh (0.48 kWh) The largest energy usage is 480 Wh (0.48 kWh), from the 20-watt bulb running for 24 hours. This shows that energy depends on both power and time—the longer a low-power device runs can surpass shorter runs of higher-power devices.

Energy is what you get when you multiply power by the time the device runs. In practical terms, that’s power in watts times hours, which you can think of as watt-hours (or kilowatt-hours when you divide by 1000).

Compute each scenario:

• 40 W for 8 h: 40 × 8 = 320 Wh (0.32 kWh)

• 60 W for 6 h: 60 × 6 = 360 Wh (0.36 kWh)

• 100 W for 4 h: 100 × 4 = 400 Wh (0.40 kWh)

• 20 W for 24 h: 20 × 24 = 480 Wh (0.48 kWh)

The largest energy usage is 480 Wh (0.48 kWh), from the 20-watt bulb running for 24 hours. This shows that energy depends on both power and time—the longer a low-power device runs can surpass shorter runs of higher-power devices.