Magnetic field of moving charges

In summary: The moving charge just drags the opposite charge around for a while, then the charge moves to the other side of the ring and the process repeats. This is in line with the theory of charged particles in circular motion. In summary, there is both theoretical and experimental evidence for the equation describing the magnetic field produced by mechanically moving charges. Electromagnetic fields have been measured in various experiments, including particle accelerators and linear accelerators. The phenomenon of water droplets orbiting around a charged ring in the Kelvin dropper experiment can also be explained by this equation. However, more research is needed to fully understand the intricacies of magnetic fields produced by moving charges.
  • #1
samueljun
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Hi! I wonder if there was any experimental measurement of magnetic field produced by mechanically moving charges.

In principle the equation is well known.
Image378.gif
(1)

But is there any experimental proof of this equation? I know it can be reformulated into this.
wire.h1.gif
(2)

My question is "Is there any experimental proof of Eq. (1)?"

I guest particle accelerator level experiment would create detectable magnetic field. I read lightning magnetise things, but it is not a direct measurement.

Please let me know if there is any DIY level experiment of measuring magnetic field by mechanical movement of charges. If it is not possible, could anyone explain why?

Thank you in advance!
 
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  • #2
What do you count as mechanical movement? Is an electron beam okay? In that case: not hard to detect.

Moving a solid object with a net charge produces tiny magnetic fields. Moving a 1µC charge by 1 km/s (that is a bullet) leads to a field of ~10nT at a distance of 10cm. Detectable, but not as DIY experiment.
 
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  • #3
mfb said:
What do you count as mechanical movement? Is an electron beam okay? In that case: not hard to detect.

Moving a solid object with a net charge produces tiny magnetic fields. Moving a 1µC charge by 1 km/s (that is a bullet) leads to a field of ~10nT at a distance of 10cm. Detectable, but not as DIY experiment.

Thank you mfb. Could you give me any reference that measures magnetic field of electron beam? I see only articles of electron beam deflected by magnetic field.
By the way, I found this article.
http://educate-yourself.org/cn/ElectronBeamMagneticField.pdf
This says that magnetic field is not due to the eq. 1 of my post but to intrinsic magnetic moment.
What do you think about this argument?
 
  • #4
I'm not aware of dedicated measurements (they probably exist, but searching for them is basically impossible, you get spammed with results of deflecting a beam with external fields), but some linear accelerators can produce beam currents larger than 100 mA. A simple hall probe next to the beam would be sufficient.

In colliders, the electromagnetic field of one beam has a significant impact on the other beam. This is called beam-beam effect and https://lhc-beam-beam.web.cern.ch/lhc-beam-beam/CERNpapers_beambeam.html.
 
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  • #5
mfb said:
I'm not aware of dedicated measurements (they probably exist, but searching for them is basically impossible, you get spammed with results of deflecting a beam with external fields), but some linear accelerators can produce beam currents larger than 100 mA. A simple hall probe next to the beam would be sufficient.

In colliders, the electromagnetic field of one beam has a significant impact on the other beam. This is called beam-beam effect and https://lhc-beam-beam.web.cern.ch/lhc-beam-beam/CERNpapers_beambeam.html.

Many thanks to mfb. I wonder if the water drop levitating (orbiting) effect of Kelvin Generator can be the example of magnetic field formation by mechanically moving charge. Otherwise it is so strange... Please have a look at the videos.



Kelvin dropper experiment is easy to set up. The reason for water drop splashing is charged water repulsion. But orbiting around the ring with static electricity is not easy to explain. The only way is that the magnetic field direction changes with time so that the electric field is induced.

I look forward to your great opinion!
 
  • #6
Orbiting around the ring is exactly what you would expect with a simple quasistatic electric attraction.
 
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What is a magnetic field of moving charges?

The magnetic field of moving charges is a phenomenon in which charged particles in motion create a magnetic field around them.

How is the magnetic field of moving charges created?

The magnetic field of moving charges is created when charged particles, such as electrons, protons, or ions, are in motion. The motion of these charged particles creates a circular magnetic field around the direction of their motion.

What is the direction of the magnetic field of moving charges?

The direction of the magnetic field of moving charges is perpendicular to the direction of the moving charged particles. This means that the magnetic field lines will form circles around the direction of motion of the charged particles.

What is the relationship between the strength of the magnetic field and the velocity of the moving charges?

The strength of the magnetic field is directly proportional to the velocity of the moving charges. This means that the faster the charged particles are moving, the stronger the magnetic field will be.

What are the practical applications of the magnetic field of moving charges?

The magnetic field of moving charges has many practical applications, including electric motors, generators, MRI machines, and particle accelerators. It is also used in everyday objects, such as speakers and hard drives, to convert electrical energy into motion.

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