Why is there no EMF induced in this circuit?

[doomer]

I have explained it in simple terms, but you have not understood it.

No, you didn't explain it in simple terms or even not at all, because that would require drawing opposing forces vectors and you didn't do that. "it's canceling because disk moves " - this is not enough.

You seem to think that by making it more complex, you will understand it more easily. That is well illustrated by your placing the short bar-magnet, under the disc.

Placing a small magnet under the disc so the field won't cross the wires is making things more complicated? nice.

Judging by your 2D diagrams, you do not think in 3D, which is a major handicap where an inherently 3D cross-product is involved. I believe that would explain your problematic understanding of the need for brushes.

I do not believe that drawing force vectors in paint is an impossible task, 3d animation is not needed, this can be achieved by making few pictures but I can make 3d model as well but first I have to know what is going on.

First we should start from this: "Working principle of a homopolar generator: due to Lorentz force FL negative charges are driven towards center of the rotating disk, so that a voltage shows up between its center and its rim, with the negative pole at the center."
So disc is charged and brushes collect this charge (no canceling here yet) current flow from the edge to the center of the disc.
Is the disc also charged when there are no brushes?? if so then soldering wires to the disc is causing voltage doubling and canceling, now I want to see this opposing canceling vectors. I think that a need to see those canceling vectors is realistic and reasonable.

This forum exist to explain things, you can give up, stop answering my questions and assume that I'm retarded or whatever, that's fine, I will ask elsewhere till I find answers and diagrams.

 

[doomer]

If you have a loop of wire and a loop of field to (dis)connect them one needs to cut the field line (Faraday) or cut the loop (contact). They need not be done simultaneously. Simple Chinese rings

By contact you mean brushes in faraday disc? If I place magnet on a wire and short this wire via switch, would I get some emf?

 

[Baluncore]

Placing a small magnet under the disc so the field won't cross the wires is making things more complicated? nice.

Yes. If the magnetic field lines do not cut the wire, then they must plunge back through the disc. The two passes, in different directions through the disc, cancel.

If it does not have a parallel vertical magnetic field, it is not a homopolar generator.

Your diagram does not show if the wire rotates with the disc, or where there might be brushes. Before the diagram can be discussed, too many reckless assumptions have to be made, or too many combinatorial conditions must be given in an answer.

Let's see if someone else is game to try to satisfy your demands.

 

[doomer]

If it does not have a parallel vertical magnetic field, it is not a homopolar generator.

What a nonsense, it seems that you knowledge about homopolar generators is worse than mine.
Check the link, this is valid brushed homopolar generator with one magnet under disc and it works, perfect parallel vertical magnetic field is not needed

Your diagram does not show if the wire rotates with the disc, or where there might be brushes. Before the diagram can be discussed, too many reckless assumptions have to be made, or too many combinatorial conditions must be given in an answer.

Did you see arrow at the top? it shows rotation of the disc, is obvious that there are no brushes, the whole discussion is about no brushes variant, well, indeed maybe someone else will be better at explaining what is going on.

 

[berkeman]

Thread is paused for a bit...