Kevin
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« on: July 15, 2011, 10:34:02 AM » |
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From my understanding, white objects absorb all visible wavelengths of light, which allow them to appear white, and black does the opposite. However, I also know that black objects absorb more heat than white objects, do these two theories contradict from each other?
In an evolutionary point of view, people who have lighter skin color tend to live in colder area, but the white skin prevents it to absorb more heat from the environment compare to black skin. So, what are the evolutionary benefits of having white skin in colder area and black skin in hotter area?
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John
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« Reply #1 on: July 16, 2011, 04:41:29 AM » |
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Black ABSORBS light, thats why it appears black.. and is warmer. White REFLECTS light, (which is why it's so bright) and is normally cooler. From an evolutionary point of view, black people have more skin protection from the sun. White people burn faster, and get skin cancer easier.
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Abinash_Sah
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« Reply #2 on: July 18, 2011, 11:46:57 AM » |
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black absorbs more light.
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Vincent_Scott
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« Reply #3 on: July 18, 2011, 12:25:13 PM » |
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The difference is that sunlight is two waves not one. UAV and UVA. One produces heat which keeps everything warm, the other is what burns people. So one absorbs more of one while the other the other. Black being heat and white being UAV.
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Nitram
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« Reply #4 on: July 18, 2011, 12:56:51 PM » |
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your understanding is totally wrong. White reflects light, black absorbs it.
Read Guns, Germs and Steel /Diamond/ for your second question
ETA
"The difference is that sunlight is two waves not one. UAV and UVA. One produces heat which keeps everything warm, the other is what burns people. So one absorbs more of one while the other the other. Black being heat and white being UAV."
What a load of nonsense lol Read a text book on basic physics.
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Arul_Seth
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« Reply #5 on: July 18, 2011, 01:14:59 PM » |
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I am sorry to tell you that you are wrong in this matter.Black surfaces absorb light whereas white surfaces reflect light.
Hope you believe in me.
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Oh_Chantima
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« Reply #6 on: July 18, 2011, 02:53:47 PM » |
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No BLACK absorbs more light, that's why you don't see any colour at all reflected off it which gives it a colour of black.
Also,it's not that people with darker skins TEND to live in warmer areas. It's because they live in warmer areas that make their skins dark. Dark skins are the result of being exposed to the sun, causing our bodies to produce melanin pigments, which darkens our skins and protects us from skin cancer.
Hope this helps explain you skepticism!
=>
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Vinod
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« Reply #7 on: July 18, 2011, 03:02:32 PM » |
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dude ,black objects absorb more lights than other colored so they appear black ! … White objects are white because almost all the light that falls on them is reflected by the material. If you want to know more visit www.physicsforums.com |
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Naren_Dutta
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« Reply #8 on: July 18, 2011, 03:11:56 PM » |
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They do not contradict, in fact they tally.
We do NOT see the color that is absorbed by objects.
black is not wavelength color. when there is no light it looks black
objects which appear black absorb light from entire spectrum(theoretically) and hence appear black
objects which appear white do not absorb any light.(theoretically)
you should know that by mixing all colors of spectrum we get white.
skin color is not much related to absorption of light
hope that helped
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ani
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« Reply #9 on: July 18, 2011, 03:21:04 PM » |
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Black absorbs all frequency ,and white reflects all frequency. so black absorbs more.
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