Knowledge of showcase light


White light is composed of colored light.Most of the visible light in life is emitted by heat radiators.Such as sunlight, light and candle light, etc., can be regarded as white light.However, the degree of whiteness is different, because these light sources contain different spectral components (spectral components, that is, the color components of light).

   How is the value of color temperature specified? Scientists compare the light emitted by a certain light source with the light emitted when an absolute black body is heated to a certain temperature. When the color components of the two are the same, the absolute black body temperature is customized at this time.The color temperature of the light source.Absolute black is also called full radiator.Refers to an object that neither reflects nor transmits, and can absorb all the radiation on it.

It is known from experiments that when the black body is continuously heated and the temperature is continuously rising, the light emitted is not white light, but colored light with color.The order of change with increasing temperature is from red-yellow-white-blue.The unit of color temperature is represented by K (the first letter in Kelvin, kehvin), starting at -273 ° C, 1K per liter (1K is not specified in international conferences, and K degrees are not written)3200k = 2927 ℃, human eyes have different color sensations to light of different color temperatures. The higher the color temperature of the light source, the more blue, and the lower the red.

The color temperature of sunlight during the day is not constant, but changes regularly over time.Morning and evening are low, and noon is high.The average color temperature of sunlight is 5600K. On sunny days, the direct sunlight is between 9 and 15 o'clock. The ratio of the three primary colors of red, green, and blue in the sunlight is basically equal, each accounting for 1/3.So it feels white.Tungsten filament lamps and civilian bulbs have lower color temperatures.There are many red-containing ingredients, giving people a reddish feeling.Fluorescent lamps contain more blue-green components.Gives people a feeling of blueish green.

Some common light sources
Candle light 1900 sunrise sunset 1850
Kerosene lamp 2000 half an hour before sunrise 2350
Ordinary civilian light bulbs 2650 9:00 to 15:00 5500
Iodine tungsten lamp 3200 9 o'clock to 15 o'clock 5000-4800
Tungsten filament lamp 3200 average daylight 5500
Photo light 3400 summer noon direct light 5800
10,000 times flash 5000--6000 in the blue sky shadow 12500
Blue sky light 19000-25000Thin cloud sky light 13000
Cloudy sky light 7500-8500Cloudy sky light 6400-7000