In life, the sunlight we see is white. After decomposing sunlight, it can be divided into seven colors, namely red, orange, yellow, green, cyan, blue, and purple. Although there are seven colors, some colors of light are invisible. Among these seven colors, blue and violet UV is invisible.
Sunlight contains powerful ultraviolet rays because it has strong energy, so after long-term skin contact, it will cause a lot of damage, such as sunburn. There is also an invisible light; the energy of this light is weaker than the red; we call it infrared light.
Many light sources can emit light because the light bulb is added when the switch is turned on, so it can emit light. Luminous paint is an exception. In a dark environment, no matter how it is heated, it will not emit light, so the luminous principle of luminous paint is different from that of ordinary light sources.
Paint has a special form of luminescence, which we call “luminescence.” Scientists in the laboratory by mixing special chemicals together to make luminous powder, and then add the luminous powder to the paint. These paints can be used in toys and stickers.
Luminous materials can always emit light, but their lighting needs conditions. The first condition is to illuminate the luminous material in a light environment. The luminous material will absorb the ultraviolet light in the light. After the energy is full, it can emit the luminous effect. The second condition is that the glow effect can only be seen in a dark environment.