Thanks for the excellent suggestions about inductors and switches.
I'll follow up on them and if I uncover other interesting issues I'll
post about them.
Now for today's question. Something that maybe ought to be simple,
but somehow I'm just not seeing the answer.
Imagine an infinite plane uniformly covered with point sources. If
each of those points emits a spherical wave coherently with each
other, then the overall resultant of all these wavelets is a plane
wave. That is Huygen's principle.
But now suppose these point sources emit mutually incoherently. I
believe one would now say the plane surface is Lambertian. But what
is a proper name for the *overall* emitted radiation pattern? It's no
longer a plane wave, is it?
I just had a thought come to me. Suppose I imagine blinking all of
the sources on for an instant, like one lobe of their sinusoidal
dipole oscillation. If they're coherent, I get a thin shell
propagating outward in space, because interference cancels
propagation in other directions. But if they're incoherent, I don't
get a shell. Instead I get a "box" full of photons that becomes less
and less dense as time goes on: some photons are shooting away
perpendicularly away from the surface, while others are skimming the
surface and making essentially no progress in the normal direction.
HOWEVER, the leading edge of this box is a plane front. It's for just
this reason that part of me strongly wants to say the radiation
pattern is still plane-like in some important way. Help me out, what
is the correct set of names and concepts to describe this? Carl
--
Carl E. Mungan, Asst. Prof. of Physics 410-293-6680 (O) -3729 (F)
U.S. Naval Academy, Stop 9C, Annapolis, MD 21402-5040 mailto:mungan@usna.eduhttp://usna.edu/Users/physics/mungan/