V = B * velocity * length, interesting, I didn't factor that.

• 4 V = 0.5 T * velocity * 150 m
• Velocity = 4 V/ (0.5 T * 150 m)
• Velocity = 4 V/(75)
• Velocity = 0.053 m/s

That is interesting because that would imply that the rotor wouldn't accelerate beyond 0.053 m/s. That would be a really interesting result in and of itself but I wonder if the back emf would actually be present in this specific case for this specific reason:

Normally, the electrons are in the moving wire and the field puts a drag force on the electrons in the reverse direction to the movement of the conductor, if you apply flemmings right hand rule in conjuction with the drag force, you will indeed get the resuls for the the induced voltage and the voltage would be in the reverse direction to the voltage I'm trying to apply.

This a bit different though. The electrons are not being dragged backwards by the field against the motion of the wire, they are accelerating forwards and dragging the wire with them.

The reason you have the back-emf issue with coils of wire is because the current flow goes in one direction on one side and the other direction on the other side and the rotors pole has to swing past both sides of the stator, so it causes back emf when it swings past the "bad" or "antagonistic" side of the stator pole.

Plus you are talking about systems with dynamic and moving magnetic fields. Homopolar motors have constant and uniform magnetic fields.

chatGPT can explain the situation better than I can: https://chat.openai.com/share/a4684164-12e3-4f4e-a9e3-55e89181d47b

ChatGPT 4 User if the lorenz force is moving a wire through a static magnetic field of consistent strenght, will there be a back emf. I assume no because the wire isn't exerting force on the electrons to move them and the electrons are the ones exerting force on the wire. 2 / 2 ChatGPT

In the scenario you described, where a wire moves through a static magnetic field of consistent strength due to the Lorenz force, the question of whether there is a back electromotive force (EMF) depends on the specifics of the system's dynamics.

The Lorenz force acts on a charged particle moving through a magnetic field, generating a force perpendicular to both the velocity of the particle and the magnetic field. When a wire moves through a magnetic field, the free electrons in the wire experience this Lorenz force. This force can induce a current in the wire if there is a closed circuit for the current to flow. The movement of the wire through the magnetic field causes a change in the magnetic flux through the circuit, which according to Faraday's law of electromagnetic induction, induces an EMF.

Regarding back EMF, it typically arises in systems like motors, where an induced EMF opposes the change in current that created it (as per Lenz's law). In your case, if the motion of the wire through the magnetic field induces a current, this current itself can create a magnetic field which may oppose the change in magnetic flux through the wire. This is the essence of back EMF.

However, in your scenario, if the electrons are not being externally driven but are instead moving due to the Lorenz force alone, the situation is a bit different. The movement of the wire (and hence the electrons in it) through the magnetic field is the primary cause of the electron movement, not an externally applied voltage or current. In this case, the concept of back EMF as typically understood in electric circuits (like in motors or generators) might not apply in the traditional sense.

Your perspective that the wire isn't exerting force on the electrons, but rather the electrons exerting force on the wire is intriguing. It's a perspective that emphasizes the fundamental interactions at play rather than a macroscopic circuit analysis.

From a classical electromagnetic viewpoint, if the motion of the wire is solely due to the motion of electrons under the influence of the magnetic field (and not an external force moving the wire independently), then the scenario becomes more about the direct interplay of magnetic forces at the microscopic level rather than traditional circuit phenomena like back EMF.

In summary, whether or not a back EMF arises in your described system would depend on whether there is an induced current that creates a magnetic field opposing the original magnetic flux change, which in turn depends on the detailed interactions and configurations of the wire, field, and circuit (if present).

V = B * velocity * length, interesting, I didn't factor that.

• 4 V = 0.5 T * velocity * 150 m
• Velocity = 4 V/ (0.5 T * 150 m)
• Velocity = 4 V/(75)
• Velocity = 0.053 m/s

That is interesting because that would imply that the rotor wouldn't accelerate beyond 0.053 m/s. That would be a really interesting result in and of itself but I wonder if the back emf would actually be present in this specific case for this specific reason:

Normally, the electrons are in the moving wire and the field puts a drag force on the electrons in the reverse direction to the movement of the conductor, if you apply flemmings right hand rule in conjuction with the drag force, you will indeed get the resuls for the the induced voltage and the voltage would be in the reverse direction to the voltage I'm trying to apply.

This a bit different though. The electrons are not being dragged backwards by the field against the motion of the wire, they are accelerating forwards and dragging the wire with them.

The reason you have the back-emf issue with coils of wire is because the current flow goes in one direction on one side and the other direction on the other side and the rotors pole has to swing past both sides of the stator, so it causes back emf when it swings past the "bad" or "antagonistic" side of the stator pole.

Plus you are talking about systems with dynamic and moving magnetic fields. Homopolar motors have constant and uniform magnetic fields.

V = B * velocity * length, interesting, I didn't factor that.

• 4 V = 0.5 T * velocity * 150 m
• Velocity = 4 V/ (0.5 T * 150 m)
• Velocity = 4 V/(75)
• Velocity = 0.053 m/s

That is interesting because that would imply that the rotor wouldn't accelerate beyond 0.053 m/s. That would be a really interesting result in and of itself but I wonder if the back emf would actually be present in this specific case for this specific reason:

Normally, the electrons are in the moving wire and the field puts a drag force on the electrons in the reverse direction to the movement of the conductor, if you apply flemmings right hand rule in conjuction with the drag force, you will indeed get the resuls for the the induced voltage and the voltage would be in the reverse direction to the voltage I'm trying to apply.

This a bit different though. The electrons are not being dragged backwards by the field against the motion of the wire, they are accelerating forwards and dragging the wire with them.

The reason you have the back-emf issue with coils of wire is because the current flow goes in one direction on one side and the other direction on the other side and the rotors pole has to swing past both sides of the stator, so it causes back emf when it swings past the "bad" or "antagonistic" side of the stator pole.

Plus you are talking about systems with dynamic and moving magnetic fields. Homopolar motors have constant and uniform magnetic fields. Especially when you use the force to spin the ring magnet instead of the wires.

Then you get to take advantage of the faraday paradox.

V = B * velocity * length, interesting, I didn't factor that.

4 V = 0.5 T * velocity * 150 m Velocity = 4 V/ (0.5 T * 150 m) Velocity = 4 V/(75) Velocity = 0.053 m/s

That is interesting because that would imply that the rotor wouldn't accelerate beyond 0.053 m/s. That would be a really interesting result in and of itself but I wonder if the back emf would actually be present in this specific case for this specific reason:

Normally, the electrons are in the moving wire and the field puts a drag force on the electrons in the reverse direction to the movement of the conductor, if you apply flemmings right hand rule in conjuction with the drag force, you will indeed get the resuls for the the induced voltage and the voltage would be in the reverse direction to the voltage I'm trying to apply.

This a bit different though. The electrons are not being dragged backwards by the field against the motion of the wire, they are accelerating forwards and dragging the wire with them.

The reason you have the back-emf issue with coils of wire is because the current flow goes in one direction on one side and the other direction on the other side and the rotors pole has to swing past both sides of the stator, so it causes back emf when it swings past the "bad" or "antagonistic" side of the stator pole.

Plus you are talking about systems with dynamic and moving magnetic fields. Homopolar motors have constant and uniform magnetic fields. Especially when you use the force to spin the ring magnet instead of the wires.

Then you get to take advantage of the faraday paradox.

V = B * velocity * length, interesting, I didn't factor that.

4 V = 0.5 T * velocity * 150 m Velocity = 4 V/ (0.5 T * 150 m) Velocity = 4 V/(75) Velocity = 0.053 m/s

That is interesting because that would imply that the rotor wouldn't accelerate beyond 0.053 m/s. That would be a really interesting result in and of itself but I wonder if the back emf would actually be present in this specific case for this specific reason:

Normally, the electrons are in the moving wire and the field puts a drag force on the electrons in the reverse direction to the movement of the conductor, if you apply flemmings right hand rule in conjuction with the drag force, you will indeed get the resuls for the the induced voltage and the voltage would be in the reverse direction to the voltage I'm trying to apply.

This a bit different though. The electrons are not being dragged backwards by the field against the motion of the wire, they are accelerating forwards and dragging the wire with them.

The reason you have the back-emf issue with coils of wire is because the current flow goes in one direction on one side and the other direction on the other side and the rotors pole has to swing past both sides of the stator, so it causes back emf when it swings past the "bad" or "antagonistic" side of the stator pole.

Plus you are talking about systems with dynamic and moving magnetic fields. Homopolar motors have constant and uniform magnetic fields.

V = B * velocity * length, interesting, I didn't factor that.

4 V = 0.5 T * velocity * 150 m Velocity = 4 V/ (0.5 T * 150 m) Velocity = 4 V/(75) Velocity = 0.053 m/s

That is interesting because that would imply that the rotor wouldn't accelerate beyond 0.053 m/s. That would be a really interesting result in and of itself but I wonder if the back emf would actually be present in this specific case for this specific reason:

Normally, the electrons are in the moving wire and the field puts a drag force on the electrons in the reverse direction to the movement of the conductor, if you apply flemmings right hand rule in conjuction with the drag force, you will indeed get the resuls for the the induced voltage and the voltage would be in the reverse direction to the voltage I'm trying to apply.

This a bit different though. The electrons are not being dragged backwards by the field against the motion of the wire, they are accelerating forwards and dragging the wire with them.

The reason you have the back-emf issue with coils of wire is because the current flow goes in one direction on one side and the other direction on the other side and the rotors pole has to swing past both sides of the stator, so it causes back emf when it swings past the "bad" or "antagonistic" side of the stator pole.