University of Central Florida (UCF) PHY1038 Physics of Energy, Climate Change and Environment Final Practice Exam

The most energy-intensive option is the one where a 100 W light bulb operates for 24 hours. To find the energy used in this scenario, you can use the formula:

Energy (in joules) = Power (in watts) × Time (in seconds).

For the light bulb, the power is 100 W, and the time is 24 hours, which is 24 × 60 × 60 seconds, totaling 86,400 seconds. Therefore, the energy consumed by the light bulb is:

Energy = 100 W × 86,400 s = 8,640,000 joules.

This significant amount of energy illustrates why this option stands out.

In contrast, the exercise bicycle uses energy at a rate of 50 W for 1 hour, which amounts to 50 W × 3,600 seconds = 180,000 joules. The electrical energy passing through the circuit is only 1,000 J over 5 seconds, which is comparatively much smaller.

Thus, when assessing these scenarios based on energy consumption, the 100 W light bulb operates longer and consumes a greater overall amount of energy, making it the correct choice.