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In order for two frequencies to "beat", they must be coherent.
That is, each frequency must be stable in phase. Color mixing, as has
already been noted, is a different kind of effect that is physiological in
nature.
Regards,
Jack
On Wed, 12 Feb 2003, SSHS KPHOX wrote:
> Today I put this question on a Waves test.
>
> 4. In color theory red light (4.8 x 1014 HZ) and green light (5.7 x 1014
> Hz) combine to yield yellow. A student proposed that this is an example of
> the beats phenomenon.
> a. What would be the beat frequency of these colors? Would this be an
> observable frequency?
> b. Is the student justified in his hypothesis?
>
> This was one of those thoughts I had without time to check whether this
> harebrained idea has any basis in fact or not. The average of these two
> frequencies is in the yellow. The difference is IR, I think. I just wanted
> to do something that was not sound. One student said that beats only
> happens with sound. I know better than that.
>
> As always looking for wisdom.
>
> Ken Fox
> Science Department Coordinator
> IB Physics Teacher
> Smoky Hill High School
> Aurora, CO
> kfox@mail.ccsd.k12.co.us
>
--
"What did Barrow's lectures contain? Bourbaki writes with some
scorn that in his book in a hundred pages of the text there are about 180
drawings. (Concerning Bourbaki's books it can be said that in a thousand
pages there is not one drawing, and it is not at all clear which is
worse.)"
V. I. Arnol'd in
Huygens & Barrow, Newton & Hooke