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[Physltest] [Phys-L] Re: Color (was LED mini-flashlight price break)



I have several color films that I discovered in the lab. The blue is
really dark and looks purple next to cyan and looks blue next to the
violet. I assume the blue, red and green are very close to "just" blue,
red and green, because when I look at light through two together it is
very dark.

Anyway, I also have yellow, cyan, violet and orange. I've found that
putting orange and cyan together I get a very nice green and putting
orange and violet together I get a very nice red. Orange and blue gives
black. Orange has very little effect when used with red or green.

Apparently, the orange film passes green and red equally. The yellow
filter appears to pass red more than green.

Why is this? Shouldn't my eyes interpret equal green/red as yellow, not
orange?

____________________________________________________
Robert Cohen; 570-422-3428; www.esu.edu/~bbq
East Stroudsburg University; E. Stroudsburg, PA 18301

-----Original Message-----
From: Forum for Physics Educators
[mailto:PHYS-L@list1.ucc.nau.edu] On Behalf Of Folkerts, Timothy J
Sent: Saturday, January 29, 2005 11:29 AM
To: PHYS-L@LISTS.NAU.EDU
Subject: Re: Color (was LED mini-flashlight price break)

One could quite easily argue the other side of the color disagreement=
-- that it is the scientists who have the definition wrong. =20

As Devil's Advocate, let me argue that color is the
perception of the= interaction of light with three widely
overlapping broadband photose= nsors. Stimulating the eye
with a) a single frequency near the overl= ap of two sensors
b) two separate frequencies near the peak responses= of the
two sensors, or c) a broad range within the response regions
= of the two sensors will all create roughly the same
response in the e= ye. All three of these are "the same color". =20

That's why three colors (not four or five or two) are
"primary". By = choosing three inks or three lights that
each stimulate primarily one= receptor, then a rather
accurate recreation of any color perception = can be produced.

=20
It's us physicists who messed it up by trying to equate a
specific co= lor with a specific wavelength ;-)

Tim F

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