Why does the color look dark when I spill water on my clothes?
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Water is a colorless and transparent liquid, but if you spill water on the ground or clothes, the color of the water-soaked part will look darker than the surroundings for some reason. Aryan Kashyap, who develops a learning app for high school students, explains why this phenomenon occurs.
Why are some things darker when wet? | By Aryan Kashyap | Medium
https://medium.com/@aryankashyap_/why-are-some-things-darker-when-wet-1ce71d8aef4e
When light hits a substance, it is reflected on the surface unless it is absorbed or transmitted. And, 'seeing an object' is synonymous with 'recognizing the light reflected by an object'. At this time, the color of what you are seeing changes depending on the wavelength of the light you receive, and the amount of light determines the brightness of what you are seeing.
Light reflection is roughly classified into two types: specular reflection and diffuse reflection. Specular reflection is when incident light (light that hits an object) hits a smooth surface and is reflected in a single direction.
Diffuse reflection, on the other hand, hits an irregularly uneven surface and is reflected in various directions. Diffuse reflection has different directions of reflected light (light reflected from an object), so the amount of reflected light that jumps into the eye at one time is reduced. The difference between specular and diffuse reflections is what makes a mirror or glass feel dazzling when exposed to light, whereas no matter how much light hits the ground or clothing, it does not feel so dazzling.
If you spill water on your shirt, the wet part of the shirt will be covered with a thin film of water. At this time, some of the incident light is reflected by the surface of the water and cannot hit the shirt. At this point, the amount of reflected light from the shirt will decrease.
In addition, some of the light that passes through the water and hits the shirt is reflected at the boundary between the air and the water, reducing the amount of reflected light from the shirt that passes through the water.
As a result, the amount of reflected light received by the observer from the wet part of the shirt is much less than the amount from the dry part of the shirt, so the wet part of the shirt is perceived as dark. is.
by Hans
The above 'phenomenon that a wet shirt looks black' can be easily explained by the basic laws of physics, but according to Kashyap, the principle is explained in more detail in the following paper published in 1988. In the end, it seems that complicated calculations and understanding of esoteric theories are required.
Fermat's Library | Why some things are darker when wet annotated / explained version.
https://fermatslibrary.com/s/why-some-things-are-darker-when-wet
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