In nature, 24 hours a day and night is a photoperiod. Sunlight is natural lighting, and light lighting is artificial lighting. Natural lighting and artificial lighting.But today’s definition has changed: heating with a black luminous body of one cubic centimeter until the luminous body melts into a liquid, 1/60 of the amount of light emitted is the standard light source, and candlelight is the standard light source. The concept of candlelight was first invented by the British, and it is a unit of luminous intensity.Īt that time, the British used a pound of white wax to create a one-foot-long candle to define the unit of candlelight. Lumen is a unit of luminous flux.Ī point light source with a luminous intensity of 1 candela has a luminous flux of “1 lumen” per unit solid angle (1 steradian).Ĭandlelight (Candela), transliteration “Candela”. For an object that is uniformly illuminated by light, when the luminous flux obtained on an area of 1 square meter is 1 lumen, its illuminance is 1 lux. Suppose the luminous flux on the facet dS is dΦ, then the illuminance E on this facet is: E=dΦ/dS.ġ lx=1 lm/㎡. The illumination/illuminance on a surface illuminated by light is defined as the luminous flux illuminating a unit area. It can be measured by an illuminance meter. The light intensity has a great influence on the photosynthesis of organisms. The international unit of luminosity is the candlelight accepted per square meter (called candela in Mainland China, Hong Kong and Macau). In photometry, “luminance” is the density of luminous intensity in a specified direction, but it is often misunderstood as illuminance. It is used to indicate the intensity of the light and the amount of the surface area of the object being illuminated.
Referred to as illuminance, the unit is Lux or lx. Illumination intensity is a physical term that refers to the luminous flux of visible light received per unit area.
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