Wow great discussion guys! Great theory.
As we stated we can put a resistance load in series with a capacitance coupling and either see the phantom voltage or make it dissapear depending on what resistance value (meter) we are using. But what happens when you put an impedance on a wire or point that is coupled through induction? I would then think that this would act like the secondary of a transformer?
There is one major difference between this and a transformer. In a transformer, almost all the flux is confined inside the core. Almost all the flux that the primary produces induces voltage into the secondary.
Lets start with a straight wire, open circuit on each end, and lets ask how much voltage is induced in this wire by a neighboring wire that has current flowing in it.
I think the answer depends on how much flux is linked. With a single straight wire, I don't see how any flux is linked. (Flux is linked when the magnetic field from one circuit flows through a turn of wire created by another circuit.) So I'm still somewhat skeptical on the whole voltage induced in a single straight wire idea.
However this isn't a problem for most real world applications. As soon as you hook your voltmeter probes to the two ends of our wire, you have created a loop. Now it would be easy to determine how much flux links our circuit, and we can all agree that a voltage is induced.
The magnitude of teh induced voltage depends on how we run our meter leads. If we run them right along the wire, we get a small loop, and we only link a little flux. If we route our meter leads in a big circle, we link more flux, and the induced voltage is higher.
If our straight wire and meter don't have any connection to ground, grounding a single point on the wire won't have any effect on the voltage we measure.
Steve