[tux3]

Nitpicking the nitpick: the energy is what's in the fields, but the electrical wires aren't just for show, the electrons do need to be able to move in the wire for there to be a current, and the physical properties of the wire have a big impact on the signal.

So things get very complicated and unintuitive, especially at high frequencies, but it's okay to say through the wire!

[a9h74j]

And as you might be alluding, particularly high frequencies: in the skin (via skin effect) of the wire!

I'll confess I have never seen a plot of actual rms current density vs radius related to skin effect.