Foot Candle is defined as the amount of illumination produced by one candle at distance of 1 foot.

Foot Candle is defined as the amount of illumination produced by one candle at distance of 1 foot.

• A. Lux
• B. Foot Candle
• C. Lumen
• D. Candela

Answer: (B)

Understanding illuminance helps here. Illuminance describes how much light lands on a surface. The foot-candle is the imperial unit for this, defined so that a surface one square foot away from a light source with luminous intensity of one candela receives an illuminance of one foot-candle. Put another way, 1 foot-candle equals 1 lumen per square foot. This contrasts with lumen, which is the total amount of light emitted by a source (luminous flux), and candela, which is the light's intensity in a given direction. Lux is the metric counterpart to foot-candle (1 lux is 1 lumen per square meter, and 1 foot-candle is about 10.764 lux).

Understanding illuminance helps here. Illuminance describes how much light lands on a surface. The foot-candle is the imperial unit for this, defined so that a surface one square foot away from a light source with luminous intensity of one candela receives an illuminance of one foot-candle. Put another way, 1 foot-candle equals 1 lumen per square foot. This contrasts with lumen, which is the total amount of light emitted by a source (luminous flux), and candela, which is the light's intensity in a given direction. Lux is the metric counterpart to foot-candle (1 lux is 1 lumen per square meter, and 1 foot-candle is about 10.764 lux).