Date: Thu, 30 Aug 2001 12:48:54 -0400

Author: Machele Bailey

Subject: Re: Color mixing apparatus

Post:

I don't know, Dick. I've heard about it done, but since we don't do this demo, I've
never played with it....jello at least sounds fun!

Chele

Richard Berg wrote:

> Do things like Jello and food coloring actually work? This stuff produces
> negative colors, and I would think that you would want positive colors to
> produce proper color mixing of lights. (Is that what the discussion is
> about?)
>
> Dick Berg
>
> On Thu, 30 Aug 2001, Machele Bailey wrote:
>
> > Perhaps jello would be a viable alternative to the liquid?
> >
> > "Robert W. Harris" wrote:
> >
> > > Poor man's version:
> > > 3 petri dishes with water and food coloring
> > > 3 overhead projectors with cardboard covering the each stage, each cardboard
> > > has circular cutout to receive one petri dish.
> > > Aim projectors at a screen. Push/twist them so the colors overlap. It
> > > works, and is nearly free, assuming you have overheads and petri dishes in
> > > the school.
> > >
> > > Br. Robert W. Harris
> > > Catholic Memorial School
> > > http://www.CatholicMemorial.org
> > > http://www.CMphysics.org
> > >
> > > ----- Original Message -----
> > > From: Earl Dolnick
> > > To:
> > > Sent: Wednesday, August 29, 2001 4:20 PM
> > > Subject: Re: Color mixing apparatus
> > >
> > > > We made one out of 3 old slide projectors. I bought 3 dichoric color
> > > filters
> > > > from Edmund that are coated on glass, and 2 inches square. They fit
> > > exactly
> > > > in place of a 35MM slide. The projectors are mounted on a board that can
> > > be
> > > > tilted with a lab jack. Each projector has a dimmer, and the images
> > > overlap
> > > > on the screen. The filters are excellent. We turn on the colors one at a
> > > > time, and it is still striking to me that when the red and green overlap,
> > > > the intersection is bright yellow. And, where all the colors overlap, the
> > > > screen is white. Red is usually brightest, and must be turned down
> > > relative
> > > > to the green and blue. Total cost was under $200. The hardest part was
> > > > finding old bulbs for the projectors.
> > > >
> > > > Cheers, Earl D.
> > > >
> > > >
> > > > Earl Dolnick
> > > > UCSD Physics
> > > > 858 534 8154
> > > > edolnick@ucsd.edu
> > > > ----- Original Message -----
> > > > From: "David Kardelis"
> > > > To: "Tap-L (E-mail)"
> > > > Sent: Wednesday, August 29, 2001 12:55 PM
> > > > Subject: Color mixing apparatus
> > > >
> > > >
> > > > > Anyone have a recommendation on a color mixing apparatus.
> > > > >
> > > > > The Leybold one I had wore out, the rubber mounts that held the mirrors
> > > > > distentigrated after many years. They failed and the mirrors fell off
> > > and
> > > > > are now cracked.
> > > > >
> > > > > I have tried colored spot lights but the effects are only so-so.
> > > > >
> > > > >
> > > > > Thanks dave
> > > > >
> > > > >
> > > >
> >
> > --
> > Machele Bailey-----Lab Manager-----Wake Forest University
> >
> > -----"Nothing shocks me. I'm a scientist." - Indiana Jones-----
> >
> >
>
> ***********************************************************************
> Experience is something you don't get until just after you need it.
> ***********************************************************************
> Dr. Richard E. Berg, Director Phone: (301) 405-5994
> Lecture-Demonstration Facility FAX: (301) 314-9525
> Department of Physics e-mail reberg@physics.umd.edu
> University of Maryland www.physics.umd.edu/lecdem
> College Park, MD 20742-4111

--
Machele Bailey-----Lab Manager-----Wake Forest University

-----"Nothing shocks me. I'm a scientist." - Indiana Jones-----

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