sophiecentaur said:
I think it would because there's a field there. A probe (infinite imdedance voltmeter) would register the appropriate voltage for the field strength and its length.
Because they have mass they would not follow any resulting curved field. I think introducing electrons is really a bad idea for this reason. It's only when in a metal (with almost zero speed,) that electrons will follow curved E field lines.
But DC is only the limit of decreasing frequency there can hardly be a step change in what happens when the current is not changing (in any case, there is no such thing as real DC because it was switched on at some time and will be switched off)
A resistor would also have an equal and opposite emf induced in it so no current would flow. I made this point before in a different context.
Well, let's clarify what I mean by "current must exist when a dynamic voltage exists". Fields are by their very nature distributed throughout space. An E field generated by a circuit, extends towards infinity, likewise for H. Likewise, the integral of E*dl can be defined for any path in space.
In order for a dynamic E/H to exist, there must be a current somewhere,
but not everywhere. This is important. Take a 2 wire transmission line. An E field exists between the wires, plus some fringing, and the H field encircles each wire, extending towards infinity. An E field exists in the space between the 2 wires. But the current is confined to the interior of the 2 wires.
Thus we can state that even under dynamic conditions, that if we confine our region of examination to a space in between the 2 wires, but excluding both wires, that we have E & H field present in said region. We can integrate around a closed path that does not include either wire or portion thereof. Hence one can say that
there is a field and an emf in this narrow spatial region, and at the same time
without a current. But remember that fields are omnipresent, but current is confined to a locale.
Outside of the wires, the influence of the current is felt in the form of fields, although the current is contained wholly within the wires. So a clarification is in order. An ac voltage in a region of space, requires the existence of ac current, but not necessarily in the same region in space. Obviously current is not present in every point in the universe, whereas E & H fields are.
Do you see what I'm getting at? In a specific spatial volume we have a dynamic E & H, but there is no current present in said volume. But there is a current nearby in the 2 wires. This current is what makes E & H possible. The emf is the integral of E over a specific closed path. But E cannot be unless current is present somewhere, but not necessarily in the region in question. The current in the 2 wire t-line is what gives rise to the proagation of E & H. That is my point. Since current is confined to a narrow region in space, while E, H, and emf are defined everywhere, most closed regions in space have E, H, & emf,
without a current in the enclosed region.
I guess I should state my point as follows. A dynamic emf somewhere in space cannot exist unless there is also a current, but not necessarily in the same spatial region. Hopefully we can all agree on that.
As far as the probe registering the right voltage, I say wait a minute. The voltage value is path dependent. The voltage value displayed on the infinite impedance VM would depend on how the leads are arranged. In free space with dynamic fields present, the emf from point a to point b, is path dependent. Re-arrange the voltmeter leads and the displayed reading changes.
So in order to define the emf, one must configure the leads along a specific path in question.
But in doing so we have introduced conductors, i.e. the test probe leads, into the picture. Like I said, attempting to define a free space emf w/o conductors is arbitrary and ambiguous. Frankly, it is pretty arbitrary to say that a region in space has an emf w/o defining a conductor with a specific shape.
I believe I've supported my position with solid facts. Anything unclear can be discussed further.
Claude
