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Why is it that we can use the Poynting Vector to find the power dissipated in a Coaxial Cable? Unlike the situation with light, where the c makes sense, inside the coaxial cable I see no reason why there should be a factor of c considered, and while we have both electric and magnetic fields, it's just not light! Any help with the reasoning/intuition?

My problem may be that I saw the 'derivation' via the example of a light wave, and not pulling from Poynting's Theorem. I'm trying to understand how electromagnetic fields can be viewed as light, and it may be that I'm just looking at it backwards. Although I still feel that a static E&M field should have some analog to a light wave that should be readily understandable.

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Did you read through the corresponding Wikipedia entry? If yes, could you point to the equation and to the c that you are referring to? –  lomppi May 15 '13 at 5:14

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