Unipolar Induction - Relative motion isn't needed!

[gravityblock]

There's been a heavy debate in regards to if the field rotates with the magnet or not.  I don't want this thread to get caught up in that debate, but there is evidence the field may even be rotating while the magnet is stationary.  Oliver Crane's theory is based on this concept with experimental observations to back it up.  Here's a video titled, "Magnetic Vortex Spin Discovery" showing a vortex flowing around a stationary magnet and also where there is no vortex when using a stationary iron slug.

Gravock

[Low-Q]

Interesting thread. I haven't read all posts carefully (and can therfor be way off the topic discussed in the latest replies), but my experienc with unipolar generators is this:


Electric energy can be generated only if the magnetic field changes through a wire. If the wire is following the magnet, that part of the wire will not generate anything. However, that wire must be coupled to another wire in order to harvest electricity at all. That second wire cannot follow the magnet, so it will be in that wire the energy is generated from. That second wire will also affect the magnetic field through the first wire (which follows the magnet), and therfor, with help from the second (stationary) wire, generate electric energy.


In short: In order to generate electricity from a unipolar generator, you need brushes. There has to be a relative velocity between the field and a wire to generate anything. To reduce friction, you can use ball bearings as a "brush". The BEMF will be there, but the efficiency of such a generator is very low, it can be hard to measure any BEMF at all. If BEMF isn't there under load of the generator, it would mean that the generator is some how fed with negative energy - energy that is less than zero. That will hypotetically happen if the generator has an efficiency of >100%. Personally I don't think we are capable of handling negative energy - yet.


Vidar

[broli]

Vidar thanks for the basic lesson on homopolar generators but we are already quite familiar with that.

This thread is mainly about 2 particular experiments.

One performed by Prof Francisco J. Muller shows that you don't need a "stationary" circuit piece in order to generate a voltage.

The other, comes from a book called "Central Oscillator and Space-Quanta-Medium", experiment shows that a voltage can be generated on the classical "disc" of a homopolar generator by spinning the magnet above clockwise and counter clockwise in an oscillating matter, showing the acceleration and deceleration being the cause of voltage generation.

Edit: Although mentioned a long time ago I would also like to add the work of Dipl. Ing. Andrija S. Radović. His experiment of confining the field is very simmilar to Muller's but the motor aspect of it is explored, see fig2; http://www.andrijar.com/dcmachines/index.html

[lumen]

There is always a lot of mysticism around homopolar generators, mostly because someone claims something that is not true.
Homopolar generators work like any other generator, a simple conductor cutting magnetic field lines, nothing more.

If you build a test rig of your own and test out every option, you will understand everything about it's operation. Even the mystery whether the field rotates with the magnet or not.

The real question in the end comes down to, Is there any way to get around the back emf?
After fully understanding it's operation,I have serious doubts that there is!
But it's possible someone could come up with something no one,s thought of before.

[Magluvin]

There is always a lot of mysticism around homopolar generators, mostly because someone claims something that is not true.
Homopolar generators work like any other generator, a simple conductor cutting magnetic field lines, nothing more.

If you build a test rig of your own and test out every option, you will understand everything about it's operation. Even the mystery whether the field rotates with the magnet or not.

The real question in the end comes down to, Is there any way to get around the back emf?
After fully understanding it's operation,I have serious doubts that there is!
But it's possible someone could come up with something no one,s thought of before.

It is funny though. If the homopolar gen can produce current in the disk, with the magnets spinning with the disk, Faraday paradox, is there drag?  And if so, what are we dragging against? And if we are dragging against something, what ever that is, if we apply power to the gen and use it as a motor, again, what are we pushing against in order for the disk and mags to be rotating together?

So if we can have drag and or acceleration, then we should be able to redesign, such a simple device as it is, and be able to move a vehicle or charge a battery, by moving the new design through thin air in say, a straight line instead of a circle. ;]

The thing that funny is, not all generators or motors will work paradoxically as the homopolar with mags attached to the rotating disk. So if it were not for Faraday and his dynamo, we would not know these things. ;]

Mags