The bearing motor

[tinman]

You are right there is a problem.  This is bloody ridiculous so I am giving up.  The average person thinks about a spinning paper clip on top of an AA battery that is sitting on top of a cylindrical magnet when you say, "homopolar motor."   I did the YouTube search and the vast majority of of homopolar motors on the first two pages of search results are the spinning paper clip type.  There are some with spinning magnets also.

There are some with spinning magnets but what the hell are we agonizing about the Lorentz forces on the wires of the paper clip for if the wires don't even move?  That's what the force vectors on the wires are for - to explain what makes the paper clip spin.  Look at my attached diagram with the two wires that make contact with the cylindrical magnet and the subsequent discussion about the forces on the wires to make the paper clip spin.   If you are talking about a spinning magnet then you should be talking about explaining the forces on the magnet itself to make the magnet spin.

I annotated your graphic to make it fit what you are actually supposedly talking about.   Note the force vectors on the wires are removed because they have absolutely nothing to do with what you are talking about.  There must be a force on the magnet itself which you haven't discussed or tried to explain properly.  The current on the left wire is in the wrong direction and you never tried to correct it and in fact it would be in the wrong direction for a spinning magnet or for a spinning paper clip.  If you wanted to make what you were talking about clear you would have put an arrow on the magnet to show the fact that it is spinning as a standard accepted convention for drawings.

It's a mess Tinman and I am giving up.  You need to learn to communicate clearly and effectively.  Now that we know what you are talking about I challenge you to explain how the spinning-magnet version of a homopolar motor works.  Likewise I am not convinced that you can explain the swirling water in the many Acca aquarium videos.  I think both a worthwhile challenge for you if you want to pursue this exploration and learning experience before you address the bearing motor but it's up to you.  I am bowing out of this discussion.

MH
I am not sure where you turned left when the rest of us went right. The homopolar motor issue came about when Mags posted his rolling(rotating)magnet experiment,which i fel is related to how the bearing motor works.

The two examples here on the homopolar motor opperate in the very same way,and is why i asked you to explain how and why this force from the wire is in one direction,and how a force exerted on a magnetic filed in this example can cause rotation.

The two examples work in the same way-->either the wire spins in a clockwise direction,or if the wire is fixed,then the equal and opposite forces cause the magnet to spin in an anticlockwise direction. So now maybe you understand as to why i asked-->how dose a force exerted on a magnetic field in this situation cause the magnet to rotate.

So now you need to think about the aquarium experiment. Is the water and bubbles turning in the direction that the wire would turn in,or are they turning in the direction that the magnet would want to turn in.?. Remember here we have ion's carrying the current,and not electrons.
Lets see if you get it right.

[MileHigh]

It just never ends Brad.  You think in half-steps when what you want to do is try to think two steps or even three steps ahead.

So now you need to think about the aquarium experiment. Is the water and bubbles turning in the direction that the wire would turn in,or are they turning in the direction that the magnet would want to turn in.?. Remember here we have ion's carrying the current,and not electrons.
Lets see if you get it right.

I can feel it.  You are thinking that if it is positive ion current that it's going to deflect in the opposite direction than what we would expect if it was say a current that stems from the motion of negative electrons.

Notice that you failed to sate if you were talking about positive or negative ions but I suppose that you meant positive ions.  Your mind is failing to go that next half step and define which kind of ions you are talking about.  This stuff happens all the time.

But here is the big problem:  If negative electron based current goes from say top to bottom, then positive ion based current will flow from bottom to top - effectively they both represent current flow in the same direction.  Therefore any force on downwards flowing electron current or upwards flowing positive ion current will be in the same direction.  You just have to stop and think and go that next half step in your analysis of the situation to realize this.  The problem is that you are stuck at the first half step and you go no further.

Like I said, I am done here.

[tinman]

It just never ends Brad.  You think in half-steps when what you want to do is try to think two steps or even three steps ahead.

I can feel it.  You are thinking that if it is positive ion current that it's going to deflect in the opposite direction than what we would expect if it was say a current that stems from the motion of negative electrons.

Notice that you failed to sate if you were talking about positive or negative ions but I suppose that you meant positive ions.  Your mind is failing to go that next half step and define which kind of ions you are talking about.  This stuff happens all the time.

But here is the big problem:  If negative electron based current goes from say top to bottom, then positive ion based current will flow from bottom to top - effectively they both represent current flow in the same direction.  Therefore any force on downwards flowing electron current or upwards flowing positive ion current will be in the same direction.  You just have to stop and think and go that next half step in your analysis of the situation to realize this.  The problem is that you are stuck at the first half step and you go no further.

Like I said, I am done here.

MH
Im not stuck,as i have done all these experiments,and seen the results with my own eyes-->no books

So i need to clarify here(as i should). In the video you posted,the guy actually touches the magnet with the wire,where as i use only the water to carry the current. So in this case,the current is being carried by ion's(mostly).
My question about which way you think the bubbles/water should rotate is a very valid question,as i was quite supprised by the results my self. All is not what it seems MH,this you can be sure of.

[MileHigh]

Yeah Brad in reading between the lines in your last posting it's apparent that you didn't think about the fact that a positive ion flow of current and a negative electron flow under the influence of the same source of potential difference will in fact be deflected in the same way by an external magnetic field.  So you were wrong.  Can't you ever simply own up to your mistakes and acknowledge that you didn't think things through?

I am burning in the point because if you are going to share some experimental data and assume a quasi teaching or data sharing role then it's doubly important as the presenter of the information and data to own up to your mistakes.  For some people it feels like they are going to faint if they admit that they are wrong.  It's not the end of the world and you aren't the pope.

That's one of the big reasons I am bowing out of this thread.  It's simply too frustrating to see/hear you go mute when you make a mistake or do an incredibly sloppy presentation of your data or setup with oversights and omissions and mistakes and then say nothing when that is pointed out to you.  I have no idea if you agree or disagree or learned something or are simply going to ignore the issue at hand like some kind of technical zombie walk.

There is not a single damn thing that is unusual or to be discovered or to be learned when it comes to sticking two live wires into a tank of water with a magnet at the bottom of the tank and watching the swirling bubbles form.  All is exactly as it seems when it comes to something as trivial as this.

[tinman]

Yeah Brad in reading between the lines in your last posting it's apparent that you didn't think about the fact that a positive ion flow of current and a negative electron flow under the influence of the same source of potential difference will in fact be deflected in the same way by an external magnetic field.  So you were wrong.  Can't you ever simply own up to your mistakes and acknowledge that you didn't think things through?

I am burning in the point because if you are going to share some experimental data and assume a quasi teaching or data sharing role then it's doubly important as the presenter of the information and data to own up to your mistakes.  For some people it feels like they are going to faint if they admit that they are wrong.  It's not the end of the world and you aren't the pope.

That's one of the big reasons I am bowing out of this thread.  It's simply too frustrating to see/hear you go mute when you make a mistake or do an incredibly sloppy presentation of your data or setup with oversights and omissions and mistakes and then say nothing when that is pointed out to you.  I have no idea if you agree or disagree or learned something or are simply going to ignore the issue at hand like some kind of technical zombie walk.

MH
I have made no mistake. All i have done is asked you some question's,that you keep avoiding,and insisting that it is me making the mistakes here.

I know the outcome of the test MH,and it would seem that from a previous post of yours,you were a little lost as to how the magnet might spin if the wire is held in position. You were about to embark on a mission to see how that may be happing,and yet it happens the same way as if it were the wire spining.

I think some times MH you get lost in thread's,and this one has left you behind. I knew that this may be a topic that you didnt understand when you said that the bearing motor would only rotate in one direction. But here you are saying it is me that is lost,and bumbling everything up.

There is not a single damn thing that is unusual or to be discovered or to be learned when it comes to sticking two live wires into a tank of water with a magnet at the bottom of the tank and watching the swirling bubbles form.  All is exactly as it seems when it comes to something as trivial as this.

And yet you had to go and think about how the forces must be acting to get the magnet in a homopolar motor spining
Quote: Also I have been thinking about a homopolar type of setup where the wire remains stationary and the magnet does indeed spin.  My preliminary thoughts are that the magnet will spin but not because of some kind of a pushing force on the magnet due the force on the external wire.  It's more complicated than that and I believe the current has to flow through the cylindrical magnet itself for the magnet to spin.

This is what i mean MH.
In both cases the current flows through the magnet,and in both cases the current dosnt have to flow through the magnet,as long as the magnetic field is present in both cases. So this means that in both situations,the force creating either rotation(magnet or conducting wire)is the very same thing,only in the opposite direction to each other.

So please MH,dont come here and try and belittle me when you yourself missed something so obvious. If this is where your books have taken you MH,then i am in no way interested in them. This is a very good example where actual experiments trump book's.

When this sinks in,then you will find my question (how dose a force imparted on a magnetic field cause the magnet itself to spin in this situation) not so stupid. You hold the wire in place,the magnet spin's-->you hold the magnet in place,and the wire spins in the opposite direction-meaning the force doing the work is the very same,and has nothing to do with having to send current through the magnet it self.