Final answer:
For a light bulb with three power settings that don't include zero, at least two filaments are required. They achieve varying power levels by being switched on separately or together. This concept is integral to electrical engineering and sustainable building practices.
Step-by-step explanation:
The question regarding the minimum number of filaments needed for a light bulb with three power settings can be answered using a concept from electrical engineering. To have three distinct power settings, the light bulb would need at least two filaments. The settings would work as follows: one filament on for low power, the other filament on for medium power, and both filaments on for high power. The power consumption related questions discuss the use of energy in a household context and strategies for efficiency, which are essential concerns in environmental engineering and sustainable building practices. Reducing power consumption and improving efficiency are ways to lower electricity bills and reduce environmental impact.