FC meaning in Chemistry ?

A foot-candle (sometimes foot candle; abbreviated fc, lm/ft2, or sometimes ft-c) is a non-SI unit of illuminance or light intensity. The foot-candle is defined as one lumen per square foot. This unit is commonly used in lighting layouts in parts of the world where United States customary units are used, mainly the United States. Most of the world uses the corresponding SI derived unit lux, defined as one lumen per square meter.

The unit foot-candle is defined as the amount of illumination the inside surface of a one-foot-radius sphere would be receiving if there were a uniform point source of one candela in the center of the sphere. Alternatively, it can be defined as the illuminance of one lumen on a one-square foot surface with a uniform distribution. Given the relation between candela and lumen, the two definitions listed are identical, with the second one potentially being easier to relate to in some everyday situations.

One foot-candle is equal to approximately 10.76 lux. In practical applications, as when measuring room illumination, it is often not needed to measure illuminance more accurately than ±10%, it is sufficient to think of one foot-candle as about ten lux.