What is the unit of illumination produced on a surface from a point source 1 foot away?

The unit of illumination produced on a surface from a point source one foot away is referred to as a foot candle. This term specifically describes the amount of light that reaches a surface one foot away from a light source. It is a measure of illuminance, which quantifies how much light is falling on a surface area. When one lumen of light illuminates a surface area of one square foot, it produces an illuminance of one foot candle.

In this context, the other options represent different concepts related to light. Lumen refers to the total amount of visible light emitted by a source and is a measure of luminous flux, not illumination on a surface. Candlepower measures the intensity of light emitted in a particular direction and is not directly related to how much light strikes a surface from a specified distance. Ballast refers to the device used to regulate the current to fluorescent and other types of lamps, which is unrelated to the measurement of illumination. Thus, foot candle is the appropriate term for the unit of illumination in this scenario.