10. LIGHT AND DARK COLOR TONES (WHEN THE INTENSITY OF THE FALLING LIGHT CHANGES)

10. LIGHT AND DARK COLOR TONES (WHEN THE INTENSITY OF THE FALLING LIGHT CHANGES) 

And now we are back again to the topic of coloration and will  consider, why there are substances painted identically, but at the same time  some of them have the lighter tones and others are darker.

At first the color of any substance under the rays of "light" falling on it (visible photons) becomes lighter. And with decreasing intensity of falling "light" -  i.e. at nightfall - the color tone becomes darker and darker. And at a minimum illumination all substances seem dark dark gray, almost black.  The explanation for this is such.

When approximately the same percentage of visible photons of all colors is contained in "light rays" emitted or reflected by the source of "light",  our visual analyzer does not distinguish between individual colors - i.e. it does not fix the prevalence of visible photons of  some one color. Our brain just characterizes the color of this "light ray" as "white", "light" apparently, because it's great the total number of visible photons entering into the eye per unit of time.  

When any substance exposed to bombardment by elementary particles (which include the visible photons), in response to this its chemical elements emit from the periphery own visible photons, whose quality determines the coloration of this substance. Together with the emission of own visible photons there occurs a reflection of falling "light rays".

In the light ray consisting of the emitted and reflected visible photons will predominate the visible photons, causing the coloration of the substance, because  in the composition of the falling "light ray" the visible photons of the same color also are necessarily present.

Addition of reflected photons to the emitted makes the total "light rays" lighter - more "white". 

As a result, the greater the intensity of the falling "light" (i.e. the more photons in the falling "light rays", the lighter becomes the tone of color coloration of the substance.

And the more the intensity of the falling "light", the more the substance color approaches the white. This arises when the number of reflected visible photons greatly exceeds the number of emitted.

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And now let's talk about why with decreasing the intensity of the falling "light rays", the tone of substance coloration becomes darker and darker. The explanation will be opposite the previous one.

The lower the intensity of the falling "light ray", the less the intensity and of the reflected  - i.e. the less number of visible photons falls per unit of time on the elements of substance, the less number of them will be reflected.  Therefore, the less light, less bright will be a visual sensation created by the total emitted-reflected "light ray".   Respectively the tone of this substance color will be darker.

And in addition to this, the less the intensity of falling "light rays", the less the number of emitted visible photons. I.e. in response to decrease in the number of bombarding particles the number of emitted particles reduces. As a result the "light shade" ("whiteness") of the total  emitted-reflected "light ray" also decreases due to the decrease of the number of emitted visible photons in its composition. Therefore the coloration of substance becomes  darker and darker.

While the intensity of falling "light rays" decreases, substance color more and more approaches to black. I.e. at nightfall the substance turns black (becomes dark). This is explained by the fact that there is a decrease of the number of emitted visible photons causing this or that coloration of the substance, due to the fact that there is a decrease of the number of falling particles, which can enhance the degree of transformation of peripheral particles and force them to leave the element.

Thus, black color is it is the absence of color caused by absence (complete or almost complete) in the total emitted-reflected "light ray" of any visible photons.

White color - it is also the absence of some specific color. However, unlike the black color the presence of white color is caused by the presence of significant amount of visible photons of all colors in the total emitted-reflected "light ray".