Behavior of compasses AFTER the magnetic pole

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Discussion Overview

The discussion revolves around the behavior of compasses in relation to the Earth's magnetic poles, particularly focusing on what happens when one crosses the magnetic south pole. Participants explore the implications of compass orientation in different geographic and magnetic contexts, considering both theoretical and practical aspects.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant asserts that a compass points towards the south magnetic pole, which is near the north geographic pole, and questions what happens when crossing the magnetic south pole.
  • Another participant challenges this assertion, stating that the compass needle will rotate 180 degrees upon crossing the south pole, indicating that the magnetic field points skywards in that region.
  • A later reply seeks clarification about the compass behavior in the area between the magnetic south pole and the north geographic pole, suggesting that the compass may still point towards the geographic south due to the radial and tangential components of the magnetic field.
  • Further discussion clarifies that the compass points to the magnetic pole and does not account for the geographic pole.

Areas of Agreement / Disagreement

Participants express differing views on the behavior of the compass when crossing the magnetic south pole, with no consensus reached on the exact nature of the compass's orientation in that region.

Contextual Notes

Participants reference the behavior of the compass in relation to the magnetic field's orientation, but there are unresolved assumptions regarding the definitions of geographic and magnetic poles and the conditions under which the compass operates.

jaumzaum
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So I know that a compass points to the south magnetic pole, that is near the north geographic pole. Let's consider the Earth to be a magnetized bar with all 4 poles aligned (for didactic purposes). The compass will try to "follow" the south magnetic pole, so, if I am in the Equator for example, it will point towards the geographic North. What if I pass the magnetic south pole (I am below the geographic north and above the magnetic south pole)? In my understanding the compass will continue to points towards the south magnetic pole, but in that case it will be pointing towards the opposite way, the geographic south!

Is this statement correct?
 
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No. The way you set up your scenario means the needle will rotate 180 degrees when you step over the south pole.

Provided it's a very sensitive compass: the magnetic field there points skywards !

Wiki pic:

compare lower left needle with lower right

1589497693236.png
 
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BvU said:
No. The way you set up your scenario means the needle will rotate 180 degrees when you step over the south pole.

Provided it's a very sensitive compass: the magnetic field there points skywards !

Wiki pic:

compare lower left needle with lower right

View attachment 262789

Thank you @BvU. Exactly in the magnetic south I am sure it will, but what about a little to the right of it, e.g. in the middle ground of the south-magnetic and north-geographic? I would say the field would have a much higher radial component, but the tangential component there will not be zero, and will make the compass point towards the geographic south, am I right?
 
jaumzaum said:
e.g. in the middle ground of the south-magnetic and north-geographic
I thought that's not in your scenario

jaumzaum said:
magnetized bar with all 4 poles aligned
Did I misinterpret this ? 2 magnetic and 2 geographic is all I could think of.

jaumzaum said:
e.g. in the middle ground of the south-magnetic and north-geographic
...
the compass point towards the geographic south, am I right
Yes. The compass points to the magnetic pole. It does not know about the geographic pole.
 

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