Iron rod - will flux link with disk above it

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Discussion Overview

The discussion revolves around the interaction between a vertical current-carrying iron rod and an aluminum disk placed above it, specifically focusing on whether magnetic flux links with the disk and the implications of using AC versus DC current.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions if the type of current (AC or DC) affects whether flux links with the aluminum disk, suggesting that it may not matter unless considering induced EMF.
  • Another participant notes that the magnetic field around a vertical rod, according to the cork-screw rule, should be circular, implying no flux links with the disk.
  • A participant references a video that suggests the disk may be repelled, indicating that flux might link with it, leading to confusion about the initial assumption.
  • Some participants clarify that the situation with a vertical wire differs from that of a solenoid with horizontal coils, which may affect the magnetic interactions.
  • There is a discussion about whether the solenoid behaves like a bar magnet, with some participants agreeing that it is a close approximation.
  • Participants express uncertainty about the relevance of AC versus DC current in this context, with some presuming it to be irrelevant.

Areas of Agreement / Disagreement

Participants express uncertainty and differing views regarding whether the magnetic field links with the aluminum disk and the implications of AC versus DC current. No consensus is reached on these points.

Contextual Notes

Participants note the differences in configurations (vertical rod vs. solenoid) and the potential implications for magnetic interactions, but do not resolve the uncertainties regarding flux linkage or the relevance of current type.

jsmith613
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If an aluminium disk is placed above a COMPLETELY vertical current carrying iron rod will any flux link with the aluminium disk...


Firstly, does it matter if the current is AC or DC. I presumed not as the only difference is that the magnetic field will vary in one case and stay constant in the other. The type of current would only be important if we were considering induced EMF.

Secondly, here is what I thought (but was not sure it was correct):
The rod is completely vertical so, as per the cork-screw rule the magnetic field should be circular around the rod. This would imply NO flux links with the aluminium disk.
However, on watching the following clip (first 40 seconds):

it seems I may have been mistaken. The only way I can see that the metallic disk is repelled is if flux DOES link with it. Perhaps also I am not comparing like with like.
 
Last edited by a moderator:
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perhaps this image will help
attachment.php?attachmentid=154620&d=1339056751.png
 
jsmith613 said:
Perhaps also I am not comparing like with like.
In your example, you have a vertical wire. In the video is a solenoid, made up of horizontal coils of wire. Different situations.
 
Doc Al said:
In your example, you have a vertical wire. In the video is a solenoid, made up of horizontal coils of wire. Different situations.

I realized that after...in my situation, however, would the disk be repelled...I presumed not as the magnetic field does not link with the disk...is this correct?

also would I be correct in thinking that the solenoid behaves like a bar magnet?
 
Last edited:
jsmith613 said:
I realized that after...in my situation, however, would the disk be repelled...I presumed not as the magnetic field does not link with the disk...is this correct?
That's what I would say.
also would I be correct in thinking that the solenoid behaves like a bar magnet?
Yes, close enough.
 
Doc Al said:
That's what I would say.
.

thanks a lot :)
 
Doc Al said:
That's what I would say.

Yes, close enough.

Is it irrelevant whether it is AC/DC
again I presumed it would be irrelevant?
 
jsmith613 said:
Is it irrelevant whether it is AC/DC
again I presumed it would be irrelevant?
I don't see how that would be relevant.
 
Doc Al said:
I don't see how that would be relevant.

ok thanks a lot :)
 

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