[alancalverd]

Is 1 mm/s realistic for you?

See reply #451 above.

It uses conventional current, as if we didn't know about electron yet.

All classical electrodynamics uses conventional current. Some conductors use hole mobility, so the classic sign convention just gives us consistent models. And in my book 0.1 mm/s is a good as stationary compared with c.

[hamdani yusuf (OP)]

Is 1 mm/s realistic for you?

See reply #451 above.

It uses conventional current, as if we didn't know about electron yet.

All classical electrodynamics uses conventional current. Some conductors use hole mobility, so the classic sign convention just gives us consistent models. And in my book 0.1 mm/s is a good as stationary compared with c.

The article I quoted disagrees.

[alancalverd]

The article I quoted disagrees.

Then it was clearly written by someone who knows nothing of electrodynamics, or is unable to evaluate his own equations

[hamdani yusuf (OP)]

The article I quoted disagrees.

Then it was clearly written by someone who knows nothing of electrodynamics, or is unable to evaluate his own equations

Maybe you can tell him his mistakes so they won't be more widespread.

https://physics.weber.edu/schroeder/
Daniel V. Schroeder
Department of Physics and Astronomy
Weber State University
1415 Edvalson Street, Dept. 2508
Ogden, UT 84408-2508
USA
Office: Tracy Hall Science Center 322
Phone: (801) 626-6048 (messages are checked infrequently)
email: dschroeder@Weber.edu

Biography
I was born in St. Louis, Missouri, and grew up in the suburb of Webster Groves. From 1980-84 I attended Carleton College, and from 1984-90 I was a graduate student at Stanford University, where I spent most of my time at the Stanford Linear Accelerator Center. I taught physics at Pomona College for one year and at Grinnell College for two years before coming to Weber State in 1993.

[alancalverd]

The most obvious mistake is using v to denote two different speeds.

Next, is a failure to provide a numerical value for his derived magnetic force and compare it with experiment.

[hamdani yusuf (OP)]

The most obvious mistake is using v to denote two different speeds.

This can be simply solved by adding indices or subscripted letters.

Next, is a failure to provide a numerical value for his derived magnetic force and compare it with experiment.

I asked chatGPT to calculate Lorentz force using relativistic method, it first derived it into classical Amperian equations, and only then it produced numerical values. Gemini somehow refused to provide numerical calculations and keep making excuses that classical formula is adequate to get accurate results, while keep insisting that relativistic explanation provides a deeper understanding of the underlying mechanism.

[hamdani yusuf (OP)]

What I see common in relativistic explanation of Lorentz force is inference that charge density of electrons and metal ions are equal in the lab frame, although the electrons' movement is the cause of the electric current, while the metal ions are stationary. This is based on the observation that test particles stationary relative to the current carrying wire doesn't experience force. But somehow the situation changes when the test particle is moving relative to the wire.

[alancalverd]

This can be simply solved by adding indices or subscripted letters.

Which he didn't do.

[hamdani yusuf (OP)]

This can be simply solved by adding indices or subscripted letters.

Which he didn't do.

He mentioned the reference frame right before the equation.

[hamdani yusuf (OP)]

The results in the last experiment has a pattern.
The first graph shows the voltage measurement against the weight/charge ratio of the salts.


The second graph shows the voltage measurement against the weight/charge ratio of the salts, when the charge of MgCl2 is "corrected" to make the graph linear.


The second graph shows the voltage measurement against the weight/charge ratio of the salts, when the molecular weight of MgCl2 is "corrected" to make the graph linear.

The next step is to conduct the experiment with other ionic solutions, like HCl and LiCl. I didn't use them because of their hazards, or economic consideration. But with the latest development, it becomes necessary to rule out some uncertainties.
Perhaps I also need to experiment with different shapes and materials for the conductor below the ionic solutions.

[hamdani yusuf (OP)]

I Always Wondered Whether Electro-Magnetic Fields are Even Real?!

I was always wondering whether the electromagnetic fields are real or just mathematical objects. This is how I understand it now after some years of studying physics.

And here's some comments.

I believe that magnetic "Lines of Force" are a nonsensical construction that emerged because the iron filings used to explore magnetic fields arranged themselves into lines. The field is clearly continuous, and any lines made visible from iron filings are an emergent property of iron filings sprinkled onto the paper over a bar magnet. All this should be obvious, but one still runs across people that speak of "lines" as if they were a fundamental part of nature.

Electro-Maganetic fields are as real as gravity!  Math is just a language to describe reality.  They are both testable and so are scientific realities.

Magnetic field lines are no more real than contour lines on a map or isobars on a weather chart.
 Magnetic field lines are drawn in line with the field gradient, whereas the others I mentioned are perpendicular to their gradients.

[hamdani yusuf (OP)]

I didn't expect to read this comment, so I checked it with ChatGPT.

Excellent presentation. Thanks. It seems to me that there's another conundrum. I read some where that the vector cross product does not exist in any randomly chosen number of dimensions. It does exist in 3 dimensions and in 7 dimensions. This means that you can't imagine that there are 4 dimensions of space because maxwell's equations would not work. But you can imagine that there are 7. The conundrum will be, however, if the 7 dimensional meaning of cross product is the same as the 3+1d version if we are trapped in a 3+1d brane in  7+1d space. But it's it the same? If not, that could eliminate the possibility that we live in universe with a higher number of dimensions - wouldn't it?

[hamdani yusuf (OP)]

Electromagnetic force on parallel wires

This equipment shows the electromagnetic force acting on two parallel current carrying wires. When the currents are in the same direction, there is an attraction force between the two wires. When the currents are in the opposite direction, there is a repulsion force between the two wires. The force is caused by the interaction of the circular magnetic field produced by each wire.

This setup is interesting. It seems sensitive enough to show small force between the wires. I think I'll try to replicate this experiment to investigate an idea from the comment section in another video explaining magnetism as a relativistic effect.

If the conductor is shielded with a conducting foil eg. Aluminum, your theory does not work because electric charges do not interact thru the shield. But the constant magnetic field passes thru the non magnetic shield  as every pupil knows. How comes that?

[hamdani yusuf (OP)]

A comprehensive theory of magnetic force should be able to explain various phenomena, including this one.

Physics Demo -- Jumping Ring

A solid metal ring is placed on an iron core whose base is wrapped in wire. When DC current is passed through the wire, a magnetic field is formed in the iron core. This sudden magnetic field induces a current in the metal ring, which in turn creates another magnetic field that opposes the original field. This causes the ring to briefly jump upwards.

If there is a cut in the ring, it cannot form current inside it, and thus will not jump.

When the ring is cooled in liquid nitrogen, the resistance of the metal is lowered, allowing more current to flow. This lets the ring jump higher. However, the magnetic field curves away at the top of the iron coil, meaning with DC power, the ring will never fly off the top.

When AC current is passed through the wire, the ring flies off the top of the iron core.  This is due to the fact that the current lags the emf by 90 degrees in inductors (which is what we have here).  This yields forces on the ring that are always pointing upwards, even as the current oscillates.

Some discussion in the comments section.

No, the current inducted in the ring is always the opposite direction of the current in the coil, so the magnetic field of the ring always opposes the iron core's, and always is repelled. Think of the AC current demo, the current's direction is switching 60 times a second, but the ring only moves away from the coil.

well its not exactly accurate although close. When dc is connected you have an initial changing magnetic field- as the dc current rapidly changes from zero to full current flow, this change in magnetic field induces current in the ring and it jumps. But the dc current reaches a peak and is then steady non changing current, therefor can no longer induce current in the ring. In the ac current, the magnetic field is constantly changing, therefor current constantly induced in the ring, so keeps goin

What's the relativistic version of this experiment?