magnetic field produced by a current flowing in a conducto 3

[arivel]

Hi everyone .
Can you clarify something for me?
if a current flows in a linear copper wire, a magnetic field is created arranged on a plane orthogonal to the conductor of electric current.
if instead of a full section copper wire I use a copper or aluminum tube, is there a magnetic field inside it or not?.
I asked the same question in an international physics forum without getting an answer, let's see if there are engineers who can answer this question.

 

[3DDave]

https://www.vedantu.com/iit-jee/magnetic-field-due-to-infinite-wire-in-cylinder

 

[arivel]

why does it say that there is no electric field and no current? .
Maybe because it refers to a radial field? .
in my case the tension is applied to the two ends of the tube.

 

[hacksaw]

If you break the tube up into separate wires, each with identical currents, you can calculate the fields inside.

 

[arivel]

I don't want to calculate it, but I would like to know if it is present or absent.

 

[3DDave]

What is most interesting is that there are hundreds of explanations on the internet for this question.

Which ones have already been read before coming here?

 

[hacksaw]

Go to the search engines to get an answer, come to eng-tips to understand how.

 

[arivel]

@3DDave
There are controversial answers on the internet.
some say that it is uniformly zero and others say that it is zero only at the axis and increases as one approaches the internal surface.

 

[3DDave]

You are the speaker guy. I presume this is some extension of that line of inquiry.

Anyway, if you can provide a link to a physics department that demonstrates it is not zero, please do so.

Do not bother with links to audiophile hobbyist sites.

 

[MagBen]

this is right and easy to explain. at the center, B is symmetrically cancelled out; off the center, the B is larger at closer to ID, lower at far distance to ID, the naked B = the difference in between. So the higher the off center, the higher the difference and the higher the naked B.
. This is a good way to think and help you to understand.

 

[hacksaw]

Amperes law provides useful insite with a bit of calculus!

 

[electricpete]

> I use a copper or aluminum tube, is there a magnetic field inside it or not?

Are we talking about the field in the empty/nonconducting area "inside" (*) of a hollow cylindrical conducting tube carrying current in the axial direction?

I'll assume there's no magnetic material and the frequency is low enough that there are no wave effects.

Then I would say the magnetic field inside is zero:
[ul]
[li]Radial field must be 0 by symmetry (there is no angle-independent loop path for flux)[/li]
[li]Circumferential field is 0 due to Ampere's law (examine a circle path centered on the axis, it has no enclosed current, Hc=0/[2*pi*r]).[/li]
[li]Axial field is 0 since there is no current flow in the radial or circumferential directions of the cyclinder[/li]
[/ul]

(*) Maybe I have misunderstood the meaning of "inside". I see the vedantu link above talks about field "inside the thick part of a hollow cylinder", which is something differernt.