On Fri, 06 Apr 2007 16:29:07 -0700, Jim Kelley wrote:

Roy Lewallen wrote:

As others have pointed out, it's risky to treat c as a variable or
medium-dependent speed.

Roy -

The convenient thing about using medium dependent c in that equation
is that we can use things such as index of refraction or velocity
factor to convert from vacuum 'c' to 'c' in another medium. The fact
that it makes the results of the calculation more accurate tends to
mitigate any risk that might be encumbered when using it.

To require that only vacuum c be used in the equation to me seems
overly authoritarian. I wonder how you feel about the speed of sound? :-)

73, Jim AC6XG

The speed of sound in a vacuum is measured using the sound of one hand clapping.

Walt