|MadSci Network: General Biology|
Initially, thereís two ways to understand the question. Youíve mentioned the darkening of skin when exposed to ultra-violet rays. It happens because light rays in ultra-violet range are more energetic than the other colors of visible light spectrum. The skin, when exposed to these rays, produces melanin, a substance that acts like a solar filter, protecting the skin from burning. Other frequency rays (the frequency determines the color of light) donít make the skin release melanin as the ultra- violet does... BUT, by the Physics point of view, every atom (and so your skin cells) reacts to the light, which is made of photons. These photons interact with the electrons of the atoms in your cells, producing vibration on these atoms. Itís the molecular description of heat. If the light rays excite your atoms enough, your local nerves, and then your brain, will react and feel this heat. Thatís a kind of ďneurobiologicalĒ detection. Hope this is useful D..! Any doubts to firstname.lastname@example.org
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