The bearing motor

[Magluvin]

This will be interesting to see.  My guess is that it will not turn without the shaft, but, that is what testing is about...
we will see. 

Good luck.

Bill

Also, say we replace the ball bearings with just brass bushings style bearings. Would it still spin, and in either direction? If not, then I have to conclude that we need those rotating balls in the bearing to do their thing.

Mags

[tinman]

Guy's
No current need flow through the magnet in order for the magnet to spin. The opposite effect to this can be seen in the homopolar generator. Here we know that the magnets can be fixed or rotate with the disc,and a CEMF will still be produced when a load is applied to the output current.
There is a flaw in the way that the homopolar generator is set up,and this flaw is what causes the CEMF-->wonder if you guys can work out what it is. The force produced in the homopolar motor that causes rotation of the magnet or wire will give you the answer.

When a current is passed through a magnetic field,there is a clamping effect that takes place between the magnetic field and it's producer(the magnet).The same clamping effect can be seen in the homopolar generator between the copper disc,and the fixed magnet version. Only when a current is flowing through the disc ,dose this clamping effect take place between the disc and the fixed magnets. When a load is applied to the current output of the disc,a CEMF is produced between the disc and the fixed magnets. Only your frame of reference has decided that the magnets art spining,as your frame of reference is stationary with the magnets.

Now-what about when the magnets are rotating with the disc. Well this backs up my claim that an equal and opposite force between the wire and the magnet is there. Here we have a case where no current is flowing through the magnets,but the magnetic fields have clamped to the magnet,and the CEMF is now between the magnets field and the wire/brushes that the current is flowing through on the outer edge of the disc-->the homopolar motor effect.

[gravityblock]

Seems to have a lot of torque.  Its odd that current runs through one bearing opposite of the other but both drive the same direction.  Makes me think that the wires could be just connected the the ends of the axle and give it a spin.  Other than that, the balls rotating with current through them must be altering the fields they produce, setting up a continuous push pull field orientation.  But for it to be able to spin either direction regardless of the current direction is the puzzle.

Mags

It can spin in either direction since the polarity of the magnetic field reverses with a change in the current direction (there's no net change, so the force is in the same direction).  This is a universal motor where it runs on both AC and DC.


Gravock

[gravityblock]

Tinman:

So what is the reason for stating that it's not surprising that the motor runs the same way when you flip the polarity?  The reason is very simple.  For starters we know that the motor runs because of the Lorentz force.  That force vector is the crossproduct of the current flow with the external magnetic field.   We also know that in this case the current flow itself produces the external magnetic field.  So if you reverse the current flow, you also reverse the direction of the external magnetic field.  So it's like a double-negative and you end up with a force vector in the same direction when you flip the polarity of the applied voltage and do the cross-product.

MileHigh

Well said!


Gravock

[tinman]

Well said!


Gravock

So what is the reason for stating that it's not surprising that the motor runs the same way when you flip the polarity?  The reason is very simple.  For starters we know that the motor runs because of the Lorentz force.  That force vector is the crossproduct of the current flow with the external magnetic field.   We also know that in this case the current flow itself produces the external magnetic field.  So if you reverse the current flow, you also reverse the direction of the external magnetic field.  So it's like a double-negative and you end up with a force vector in the same direction when you flip the polarity of the applied voltage and do the cross-product.

MileHigh

No,not well said,and this was MH comment before he knew or read all the details.
The motor will run in either direction REGARDLESS of weather it is supplied with an AC current or a DC current. So once we use a DC current,then MH explanation go's out the window.

I think it would be a good idea gravock if you read the whole thread,and understand what is going on here before making faulse presumptions.