Which term describes the amount of light that lands on a surface?

Which term describes the amount of light that lands on a surface?

• A. Lumen
• B. Lux
• C. Candela
• D. Illuminance

Answer: (D)

Illuminance describes how much light lands on a surface. It’s the luminous flux reaching a specific area, so it tells you how bright that surface will appear. It’s measured in lux, with 1 lux equal to 1 lumen per square meter. This is the quantity IH uses to express lighting on work surfaces. Lumen is the total amount of light emitted (or reaching a surface) in all directions, not tied to a specific area. Candela is the luminous intensity in a particular direction, describing how bright the source appears along that direction, not the amount of light on a surface. So when you’re asking about the light that actually falls on a surface, illuminance is the correct term. For example, if 100 lumens land on 2 square meters, the illuminance is 50 lux.

Illuminance describes how much light lands on a surface. It’s the luminous flux reaching a specific area, so it tells you how bright that surface will appear. It’s measured in lux, with 1 lux equal to 1 lumen per square meter. This is the quantity IH uses to express lighting on work surfaces.

Lumen is the total amount of light emitted (or reaching a surface) in all directions, not tied to a specific area. Candela is the luminous intensity in a particular direction, describing how bright the source appears along that direction, not the amount of light on a surface. So when you’re asking about the light that actually falls on a surface, illuminance is the correct term. For example, if 100 lumens land on 2 square meters, the illuminance is 50 lux.