# Does moving an insulating cylinder produce a magnetic field?

• lelouch_v1
In summary, assuming that we have an insulating cylinder with a dielectric, moving the cylinder towards increases the magnetic field.
lelouch_v1
Suppose that we have an insulating cylinder with ##\rho_q##. If i move the cylinder towards ##+\hat{n}##, will it produce a magnetic field? My assumption is that since we have an insulator, then the electrons are bound and there cannot be a current, thus a magnetic field is not produced. Also, does this happen if we have a material full of dielectric?

Assassinos said:
If i move the cylinder towards , will it produce a magnetic field? My assumption is that since we have an insulator, then the electrons are bound and there cannot be a current, thus a magnetic field is not produced.
If there is charge in motion then this is a current and there is a magnetic field.
Assassinos said:
Also, does this happen if we have a material full of dielectric?
I don't understand what you are asking here. What material is full of dielectric?

vanhees71
Ibix said:
If there is charge in motion then this is a current and there is a magnetic field.

I don't understand what you are asking here. What material is full of dielectric?
Assume a sphere of radius R, and from 0 to R the sphere is filled with a dielectric of permittivity ε.

Is it charged and moving? If so, there's a current.

lelouch_v1
Assassinos said:
My assumption is that since we have an insulator, then the electrons are bound and there cannot be a current
A moving charge density is a current: ##\vec j = \rho \vec v##

vanhees71
One should add a comment to the question about the dielectric. That was a very hot question in the 19th century, where many physicists where very puzzled about the "electrodynamics of moving bodies", and it was indeed a question, what's the nature of polarization and if a moving polarized body would produce a magnetic field. This was investigated by Röntgen and Eichenwald, and confirmed that indeed a moving polarized dieelectric produces a magnetic field, which however only added on the puzzle about "electrodynamics of moving bodies".

The final solution of all these troubles was nothing less than Einstein's famous breakthrough paper in the Annalen der Physik titled modestly "On the electrodynamics of moving bodies" and lead to one of the "revolutions" in 20th-century physics, i.e., the (special) theory of relativity.

hutchphd, Delta2 and Ibix

## 1. What is an insulating cylinder?

An insulating cylinder is a type of object that does not conduct electricity. It is made of a material that does not allow electric charges to flow through it.

## 2. How does moving an insulating cylinder produce a magnetic field?

Moving an insulating cylinder creates a change in the electric field around it. This change in the electric field then creates a magnetic field, according to Maxwell's equations.

## 3. Is the magnetic field produced by a moving insulating cylinder strong?

The strength of the magnetic field produced by a moving insulating cylinder depends on the speed and size of the cylinder, as well as the material it is made of. Generally, the magnetic field is weaker than that produced by a moving conductor.

## 4. Can the direction of the magnetic field produced by a moving insulating cylinder be changed?

Yes, the direction of the magnetic field can be changed by changing the direction of movement of the insulating cylinder. The direction of the magnetic field is perpendicular to the direction of movement.

## 5. What are some real-world applications of a moving insulating cylinder producing a magnetic field?

One example of a real-world application is in magnetic levitation trains, where a moving insulating cylinder is used to create a magnetic field that allows the train to levitate and move without friction. Another application is in generators, where rotating insulating cylinders are used to produce electricity through the changing magnetic field they create.

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