Re: pinhole Color in the eye

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From: wendy derjue-holzer (wendyd@exploratorium.edu)
Date: Tue Apr 12 2005 - 11:43:03 PDT 

Message-Id: <a05010401be81baf15042@[192.168.111.61]>
Date: Tue, 12 Apr 2005 11:43:03 -0700
From: wendy derjue-holzer <wendyd@exploratorium.edu>
Subject: Re: pinhole Color in the eye

>The red light is converted into electric impulses in one rod that is tuned
>to respond to red frequencies
>The blue light is converted into electric impulses by a rod tuned to
>respond to blue light.
>
>The electric signals are sent to the visual cortex where the perception of
>magenta is created when both signals are detected in the same region of the
>retina.
>
>Paul D
>

On way to see what Paul is talking about is the Exploratorium exhibit
called Color Removal. The exhibit has white light that comes from a
film projector. The light is sent through a prism. One side comes
straight through and looks like whatever color you started with. The
other half gets spread out into a rainbow (aka the colors that make
up that light.)

A visitor can put any color filter in front of the film projector to
block out all of the colors except the filter colors. With the red
filter you get red straight through the prism and red is the only
color left on the rainbow side. If you put a yellow filter up
instead, it looks yellow straight through and on the rainbow side you
have yellow (unsurprisingly) and red and green because red and green
light make yellow light. Suppose you put the magenta filter on.
Magenta light goes into the prism. One side is magneta and but the
rainbow side shows only red and blue. There is no magenta in the
rainbow. The magenta color is made by our eye/brain putting together
red and blue. (Yellow on the other hand is in the rainbow but also
can be made by red and green light hence you see all three of those
colors on the rainbow side of this exhibit.)

I imagine you could make a version of this in a classroom.

And if anyone wants advice on exhibits to match any of your areas of
study, ask me. I'm happy to help.

-Wendy
415 674-2867
Exploratorium Field Trips

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