What is a foot-candle?

A foot-candle is defined as a unit of measurement for illuminance, which quantifies the amount of light that falls on a given surface area. Specifically, one foot-candle is equivalent to one lumen per square foot. This measurement is crucial in lighting design and assessment as it directly relates to how well a space is illuminated for visual tasks. Understanding foot-candles helps lighting professionals determine the appropriate level of light for different environments, ensuring both sufficient visibility and comfort for occupants.

The other options pertain to different aspects of lighting but do not define illuminance specifically. For example, light temperature refers to the color appearance of light, color rendering relates to how accurately a light source displays colors, and brightness perception pertains to the human eye's interpretation of light intensity, all of which are distinct concepts from the direct measurement of illuminance provided by foot-candles.