What direction will a compass point at point X?

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Homework Help Overview

The discussion revolves around the behavior of a compass when placed at a specific point X in relation to a bar magnet and a soft iron ring. Participants explore the magnetic interactions and field directions involved in this scenario.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the expected direction of the compass needle and the influence of the soft iron ring on the magnetic field. Questions arise about how the iron ring interacts with the magnetic field and whether it alters the compass's direction.

Discussion Status

The discussion is active, with participants sharing their thoughts on the magnetic properties of iron and how they might affect the compass's behavior. Some guidance is provided regarding the concept of magnetic field containment, but no consensus has been reached on the compass's final direction.

Contextual Notes

There is an ongoing exploration of the assumptions regarding the magnetic field's behavior in the presence of the soft iron ring, as well as the initial conditions of the compass's orientation.

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Homework Statement


The plotting compass, initially on the left and pointing to the geographical north, is now placed at point X. Which direction it will show?
201706141303541000.jpg

Homework Equations

The Attempt at a Solution


I think the arrow will point towards the south pole of the bar magnet (to the left). Is this correct?

Thanks
 
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What are your thoughts on the soft iron ring?
 
CWatters said:
What are your thoughts on the soft iron ring?
I am not sure. Maybe the magnetic field produced by the magnet will "follow" or "carried by" the soft iron ring so the magnetic field will circle around the magnet but in the end the direction will still be from north pole to south pole. The compass is affected by magnetic field so it will point to the south pole.

So I guess I am wrong?
 
CWatters said:
Perhaps see "containing the field"...
http://www.coolmagnetman.com/magshield.htm
Oh, so the field will be "contained" by the soft irong ring, leaving a very few or maybe no field at all outside it and the compass will point to the north (same as its initial direction).

But why can soft iron ring contain the field?
 
Iron is a good conductor of magnetic fields, in effect the iron ring "shorts out" the field.

Consider a magnet in free space. Lines of flux run from one pole to the other via the space around the magnet. If you put a piece of iron near the magnet the flux finds it easier to flow in the iron so it takes a "short cut" along the iron rather than the original path.

I suppose it's similar to why there is no electric field in a conductor.
 
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CWatters said:
Iron is a good conductor of magnetic fields, in effect the iron ring "shorts out" the field.

Consider a magnet in free space. Lines of flux run from one pole to the other via the space around the magnet. If you put a piece of iron near the magnet the flux finds it easier to flow in the iron so it takes a "short cut" along the iron rather than the original path.

I suppose it's similar to why there is no electric field in a conductor.

Thank you very much
 

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