Cecil Moore wrote:
Jim Kelley wrote:
Cecil Moore wrote:
Ptotal = P1 + P2 + 2*SQRT(P1*P2)*cos(A)

According to fig. 7.1 in Born and Wolf, that's useful for showing how
light intensity varies as a function of phase, and hence position.
It's just that there's no valid way to multiply by the cosine of the
angle between two scalars.

I suspect you knew if I ever found my Born and Wolf after my
move, you would be in trouble - and you are.

No. I assumed you could find fig 7.1 and see it for yourself. The plot
has phase on the X-axis and intensity on the Y-axis. The caption reads
Interference of two beams of equal intensity; variation of intensity
with phase difference. " At the top of the page: "Let us consider the
distribution of intensity resulting from the superposition of two waves
which are propagated in the z-direction...."

The relation is useful for precisely the reason I indicated. That is
why Heckt also includes it in his book.

I deleted the rhetorical blithering from your post. And again, please
quote my remarks directly whenever you wish to discuss them.

73, ac6xg