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Author Topic: the north is the south  (Read 7001 times)

Offline erickejah

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the north is the south
« on: 26/03/2009 03:05:29 »
When I was working today I learned that the arrow in a compass always points the north pole, but when you put it in a bar magnet it points south.  :o
Quote
For historical reasons, what we call "Earth's North Magnetic Pole" is actually the south pole of Earth's magnetic field! Yikes!
http://www.windows.ucar.edu/tour/link=/physical_science/magnetism/bar_magnet_interactive.html

does anyone wants to tell me anything else that I should know for my bright future, that was teach to me in the wrong way when I was a kid?  :(


 

Offline Chemistry4me

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« Reply #1 on: 26/03/2009 05:12:41 »
Your scales are lying to you.
 

Offline Karen W.

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« Reply #2 on: 26/03/2009 06:42:24 »
I wish my scales lied to me!
 

Offline Karen W.

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« Reply #3 on: 26/03/2009 06:45:22 »
I never could read my compass properly even after people here tried to explain it to me.
 

Offline DoctorBeaver

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« Reply #4 on: 26/03/2009 08:45:10 »
Never say "The North is the South" to a Yankee!
 

lyner

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the north is the south
« Reply #5 on: 26/03/2009 09:56:10 »
The 'North Pole' of a bar magnet is, actually, called a 'North Seeking Pole'. So the Earth's N pole is actually a South Seeking pole.
So no confusion really - just sloppy language.
 

Offline Mazurka

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« Reply #6 on: 26/03/2009 10:31:11 »
It also changes round periodically (i.e. the north pole becomes the south pole and vice versa).  Although these flips happen quickly on a geological timescale, there is a time when there the earth has effectively no magnetosphere and thus little protection from the radiation of the solar wind. 

The study of Paleomagnetism has helped to confirm the theory of plate tectonics and can be useful when dating rocks as well.
 

lyner

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« Reply #7 on: 26/03/2009 19:28:20 »
At that time, they will have to collect in all the School magnets and textbooks . . . . .
 

Offline erickejah

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« Reply #8 on: 26/03/2009 20:56:49 »
how often does it changes?
 

Offline Soul Surfer

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the north is the south
« Reply #9 on: 27/03/2009 12:10:09 »
Its overdue for one now and could be on its way to changing! The earth's magnetic field is falling quite steadily. This could also have some interesting climatic changes!

Not many people are getting their knickers in a twist about this  ...  Yet!

This gives the full story  http://en.wikipedia.org/wiki/Geomagnetic_reversal

 

lyner

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« Reply #10 on: 27/03/2009 13:05:08 »
how often does it changes?
We're talking shortish 'geological' intervals. They can see magnetic stripes in the rocks forming in deep ocean trenches. The rock, when it's magnetic type, solidifies permantly magnetised with the Earth's field at the time.
Not sure how long the switch takes.
 

Offline erickejah

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the north is the south
« Reply #11 on: 27/03/2009 16:33:39 »
wow :o, this is interesting... what is going to happen to a regular compass when this change occurs?
 

lyner

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« Reply #12 on: 27/03/2009 18:03:20 »
It will point the other way.
More of problem is the expected increase in radiation levels from 'out there' whilst the field drops to zero during the changeover. The field does a lot to protect us from fast particles by making them corkscrew violently and lose their energy before they get down here, I believe.
 

Online yor_on

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« Reply #13 on: 27/03/2009 20:13:32 »
Sorry Eric, nice try though.
 

Offline erickejah

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the north is the south
« Reply #14 on: 29/03/2009 00:00:22 »
would the gps still work?
 

lyner

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« Reply #15 on: 29/03/2009 13:04:15 »
Why not?
GPS doesn't use the Earth's field afaik. Certainly, your receivers don't and the positional information of the satellites is provided in a similar way, which involves accurate timing of radio signals arriving from known positions on the globe.
« Last Edit: 29/03/2009 13:05:59 by sophiecentaur »
 

Online yor_on

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« Reply #16 on: 31/03/2009 15:12:02 »
Wasn't there some Australian guy that said that the evidence for those magnetic 'reversals' was wrong? I remember reading him some year or two ago?
 

lyner

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« Reply #17 on: 31/03/2009 22:31:36 »
One swallow doesn't make a summer.
What were the grounds for his objection.
 

Online yor_on

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« Reply #18 on: 01/04/2009 13:10:20 »
If I remembered I wouldn't ask SC :)
But this guy made sense when I read him.
Doesn't say much, huh :)

Anyway, I'll see if I can find that link.
 

Online yor_on

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« Reply #19 on: 01/04/2009 16:11:16 »
As I remember it it was a discussion on the idea of how liquid magma cools and becomes solid rock, doing so some of the minerals in the rock preserve a record of the direction and strength of the magnetic field at that time. And it is this (paleomagnetism) scientists have used to make a geomagnetic reversal time scale, showing how the Earth's magnetic field has changed direction over the past couple hundred million years or so. He had a another explanation to how they had 'lined up' magnetically in those lavas that was both simple and straightforward :) And I'm pretty sure he was a retired Geologist or Engineer from Australia. Could be wrong though, but, if someone recognize it? 'Link it up Scotty'.
 

lyner

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« Reply #20 on: 01/04/2009 18:59:06 »
I'll watch this space. . .
 

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« Reply #21 on: 04/04/2009 12:03:22 »
 

Offline syhprum

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the north is the south
« Reply #22 on: 04/04/2009 22:06:55 »
"would the gps still work", no when the Earths magnetic field fell to zero during the reversal we would lose the shielding from cosmic rays which would really louse up the satellites!.
 

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the north is the south
« Reply #22 on: 04/04/2009 22:06:55 »

 

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