Open the fifth book of art teaching materials for nine-year compulsory education and six-year primary schools (Jiangsu Children's Publishing House). The book states the "three primary colors" in this way: "Thousands of colors can be adjusted with red, yellow and blue, but no other color can adjust these three colors. They are the ancestors of the color kingdom and are called the three primary colors. "
We know that light is a wave with a certain wavelength and frequency, so the three primary colors of light are three different waves: the wavelength of red light is about 700 nm, that of green light is about 545 nm, and that of blue light is about 435 nm. It is called three primary colors because no light mixture of any color can adjust the effects of these three lights, and all lights except these three can be adjusted by primary colors. For example, mixing red and green can form a yellow effect. However, some people think that the superposition of two waves will not form a third wave, so the mixture of red light and green light will not produce yellow light, but the human eye feels similar to yellow light with a wavelength of 570~575 nm. Just like what we call white light (natural light), it is actually a reflection of the mixed effect of visible light of various wavelengths in our eyes. The three primary colors of light do not exist objectively, but are artificially defined, because the human eye has only three color-sensitive cells: red, green and blue. When we say that these cells are sensitive to red, green and blue, we actually mean that red blood cells are sensitive to long-wavelength light (red light) and insensitive to other wavelengths of light. People feel that color is like taking pictures with a digital camera. The data generated by color vision cells on the retina are processed by the brain, and color perception is generated by analyzing the ratio of red, green and blue.
Every color we talk about in art class is a substance that reflects its own color and absorbs visible light of other colors. The same is true of red, yellow and blue. These pigments can be mixed in different proportions to make various colors. Interestingly, the superposition effect of the three primary colors is white (white light), while the mixed color of the three primary colors is black, which can absorb all visible light.