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>Hi Folks,
>
>Here is a general physics question I had while I was taking general
>physics in college.  When two identical waves move in the same direction
>but out of phase by 180 degree, A*cos(a) + A*cos(a-180) = 0, the
>amplitude of the resulting wave is zero all the time.  Where does the
>energy go?
>


Nowhere - there isn't any energy.  If these are two sources half
a wavelength apart then there will be two in-phase beams at right
angles to it, and they will be carrying all the energy emitted by
the sources.  But if you are talking about one point source emitting
both identical waves simultaneously but 180o apart then that point
source isn't emitting any light or radiating any energy!

                                                Guy Cox

Dr. Guy Cox,   |                    ooOOOOOOoo
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