From: "JACK L. URETSKY (C) 1996; HEP DIV., ARGONNE NATIONAL LAB, ARGONNE, IL 60439" <JLU@hep.anl.gov>
Date: Wed, 22 Apr 1998 19:17:23 -0500
Hi Larry-
I think that the correct answer for an introductury course is this:
The constants K_e and K_m are determined by our choice of units for
electric and magnetic charge and our unit of length. The significant fact
is that these two constants are related so that their ratio, regardless of our
choice of units, is just the square of the speed of light. This fact suggests
that light is somehow related to electricity and magnetism and electric and
magnetic forces are somehow related to each other.
Regards,
Jack
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Sorry if this is a stupid question, but I'm rusty on this and none of the
H&R or Serway level books give me a good answer. My students asked, "If
free space is totally empty, why does it have impedance [of 377 ohms]?" I
was about to answer that free space isn't really empty and launch into
something about a sea of virtual particles, but then I thought I'd better
ask the list first.