# why light is consist of seven or more color not only three color?

Discussion in 'Physics & Math' started by Paul Leung, Feb 22, 2014.

1. ### AnewLife isn't a question.Banned

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in my view light is reflectant of color, not consistent of color yet likes being . take for instance a mirror is a light object,, the mirror has a frequency absorbent ratio,. a rainbow is formed through the existence of brown. )forgive me if this seems scattered or irrelative yet ideas

3. ### Paul LeungRegistered Member

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I try to do the experiment with two prism and the light source is torchlight, and below is the result.
When yellow light through the second prism, there are red, green and blue in its edge.
View attachment 7016

When blue light through the second prism, there are red, green in its edge.
View attachment 7017

5. ### el esRegistered Senior Member

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Use a DVD to get a nice spectrum. Look at it through a prism. No further separation occurs. Your pet theory fails the test.

7. ### el esRegistered Senior Member

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The image is proof that you are using a yellow HUE, not a PURE spectral yellow. You have to get as far as possible from the prism.

When using a prism and perceiving white between the yellow and blue, there is color mixing going on in that area.

A diffraction grating does a better job of color separation and you don't perceive white between the yellow and blue.

8. ### Paul LeungRegistered Member

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There is another experiment about looking through a prism.

Put a thin strip of white paper on a dark surface and look at it through a prism.
If the strip is sufficiently narrow, there are essentially only three colours to be seen: red, green and blue-violet.

And the result I got.

View attachment 7040

View attachment 7041

And the Reference:
Simple observations with a prism
www .itp.uni-hannover.de/~zawischa/ITP/prism.html

9. ### billvonValued Senior Member

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Zooming in very closely, I also see orange, yellow and blue-green.

10. ### NMSquirrelOCD ADHD THC IMO UR12Valued Senior Member

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found an interesting link when looking for spectrography, was looking for some cool pics to share..

cool pic:

click pic to website that shows you how to build your own spectrometer.

11. ### NMSquirrelOCD ADHD THC IMO UR12Valued Senior Member

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5,478
anyway, the colors you get are dependent on the light source, and the medium it travels through.
the width of the colors in the band are a result of these factors as it is used to detect atmospheres of distant planets.

12. ### el esRegistered Senior Member

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If you thwart or squeeze the dispersion of the visible spectrum, you won't see the full visible spectrum.

With prisms, what you see will depend upon how the experiment is set up. The arrangement of the source, width of slit, and distance of the viewing screen from the prism.

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14. ### Paul LeungRegistered Member

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I changed the experiment a bit to use a triangle shaped paper instead of a thin strip of paper.
And there is the result of using triangle shaped paper, the color of paper include white, yellow, magenta, cyan and pink.
The result show yellow and cyan disappeared and separate to red, green and blue when the white paper become narrow.

View attachment 7049

15. ### RJBeeryNatural PhilosopherValued Senior Member

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OK I'm assuming that you want the truth, and not just to argue. If you're seeking the truth I will help you.

As humans, we can fool our eyes to see colors which do not exist. See here for how the RGB monitors are incapable of displaying TRUE yellow, for example.

Now, contrast that with the scientific definition of what we mean by "yellow" light coming from the sun, along with every other "color"; they have very concrete ranges of wavelengths, and can be measured by machines. The sun's distribution of wavelength spectra can be seen here. Note that it is not completely uniform, but it certainly isn't restricted to only three colors! All visible colors are represented.

In the end, there is a possibility that you can "see" the red, blue and green circles in the prism separation more distinctly than the other colors because of the way our eyes perceive light (with blue, red and green cones...perhaps not so coincidentally). This would be a limitation of human perception, though, and not of what truly makes up white light.

Last edited: Apr 24, 2014
16. ### Paul LeungRegistered Member

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The camera also can get the red, green and blue circles in the prism separation more distinctly, so it mean the camera also has
limitation in perceive light, and the result of spectrum using the spectrometer also has problem too, because of the camera and eye also has
problem to perceive light. If camera can not detect light well, eye can not percieve light well, Is the result of spectrum really accurate?

You think there are limitation of human perception because you think light is consists of many color light. If it only consists of
three color light in visible light and eye see different color is only depend on three color light, there is no limitation of human perception.

If newton color theory is true, it should be easy to explain why it seem like three triangle shape overlap together when looking at a
white triangle shaped paper through the prism.

If eye perceive other color light weaker than red, green and blue is true also can not explain the pattern you looking at a white triangle
shaped paper through the prism. If you actually do the experiment about looking at a white triangle shaped paper through the prism,
it should be more clear to see there are three color light by looking at the prism when there are certain distant between the prism and white
triangle shaped paper.

And there is a device also can fully dispersed the light.

en.wikipedia.org/wiki/File:Color_Separation_Prism.jpg

can not see a little bit of yellow light.

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18. ### Paul LeungRegistered Member

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A yellow object reflect red light and green light, and it reflect yellow light if monochromatic yellow light exist. Is it really logical
to you see the monochromatic yellow light and at the same time you see the yellow which is composite of red light and green light.

19. ### billvonValued Senior Member

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20,612
Yep, that's how it works. For a simple proof of this look at your TV with a magnifying glass. You will see red, green and blue pixels - no yellow to be seen. But back up and you will see yellow colors being accurately depicted by the TV.

20. ### originHeading towards oblivionValued Senior Member

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Yes you have to take into account the limitations of the detectors you are using (your eyes).

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22. ### el esRegistered Senior Member

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So, physics would rather deal with classical wavelengths or electron volt energies of photons than biological based perceptions of colors.

23. ### exchemistValued Senior Member

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Obviously. Because the job of physics is to model the underlying reality of physical phenomena, not just how they superficially appear, to one life form.