Our usual white light is actually composed of seven monochromatic lights: red, orange, yellow, green, blue, indigo and dense. This was first proposed by Newton in 1666. Shade the room, only let this beam of sunlight enter the room, and put a special prism where this beam of sunlight shines. You will find that this beam of light passes through the prism and bends to the bottom of the mirror.
Why do objects appear colorful in white sunlight? This is because when the sun shines on an object, part of the light is reflected by the surface of the object, and the other part is absorbed by the object. The color of an opaque object passing through the object is determined by the color of the light it reflects. If an object can reflect all seven colors of light in the sun, then the object is white; On the other hand, if an object absorbs any color of light projected on it, it will appear black. Tomatoes are red because they only reflect red light and absorb other wavelengths of light. If you observe tomatoes under blue light, the situation will be different. Because tomatoes can only reflect red light, there is no red component in blue light, and it will appear black after absorbing blue light. This shows that the color of an opaque object depends on the light it reflects.
For a transparent object, its color is determined by the color of the light that can pass through it. The color of green glass is the result that it only allows green light to pass through. Colored electric lights hung on festivals and counties can display colors, not because they can emit colorful light, but because their glass bulbs only allow a certain color of light to pass through, and their illuminators are the same as ordinary electric lights. Ordinary window glass can let all kinds of light through, so it is completely transparent to sunlight. Similarly,
The color of a luminous object is determined by the color it emits. When an object is heated and burned at a certain temperature, it will emit light, which is thermal radiation. Radiative luminescence can be carried out at any temperature, but we can only see visible light waves of thermal radiation. For example, when tungsten filament is heated, it can emit infrared light invisible to human eyes at constant temperature, and can see dark red light when it reaches 500℃, reaching 1500℃.