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Compass Reversing?


WebbWalkers
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Has any one had their compass reverse poles? So a North needle is now South. One day it was fine, then the next time I used it, I find it reversed. How would that happen? And how would I go about fixing it? I would prefer not to toss it since I’ve had it for years. TIA.

WebbWalkers

WebbWalkers, it definitely sounds like your compass has reversed poles. Getting it too close to a strong magnetic force can cause this.

 

I'm sure you have played with magnets before. You know that when you place two magnets together, that they will only attract to each other in one direction, and if you turn them around, they will actually repel each other. You can call this North and South polarity. North and South attracts, while North/North or South/South won't.

 

You can think of the earth as having a large magnetic bar running from the north, thru the center core, and coming out at the south end of the world. The north end of this magnet has a southern polarity and the south end of the magnet has a northern polarity.

 

Since the earths magnetic north field actually has a southern polarity, it attracts your compass needle, which has been factory magnetized with a northern polarity. If for any reason your compass needle has it's polarity reversed, then the magnetic fields won't attract, but instead repel each other. (Technically, your reversed needle will now be attracting towards the magnetic south that has a northern polarity, but your needle's magnet may not be strong enough for this to actually happen)

 

This sound's like what has happened to your compass. Your compass has been remagnetized by another magnet with a southern polarity. Silva has information on their website about how to fix your compass that this has happened to.

 

http://www.silva.se/outdoor/products/comp_general.htm

 

I'm sure there are more scientific correct terms for what I said, but this is as best I can understand and explain it.

 

Hope it helps you understand what happened.

 

LSUFan

Edited by LSUFan
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I have had this happen. I have a bunch of very strong rare earth magnets and wanted to see how strongly they would influence the compass. I got it too close and messed up the magnetization of the compass needle. I fixed it by holding the correct end of the magnet and stroking it along the needle again. But I can't tell how accurately this reoriented the needle magnetization. It would not have to be perfect. Also, when it was messed up, it was not magnetized directly along the length and the needle would pull down toward the ground. It was a very cheap compass, so I didn't worry too much about it. But they really should make the needles from material that is more resistant to remagnetization.

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A strong physical shock can also alter magnetic properties. I remember a physics experiment from school - the instructor took a 4' long iron bar, and touched it to a pile of paper clips. Nothing happened. Then he aligned the bar along north/south, took a small sledge hammer, and whacked the end of the bar really hard, about 20 times. Then he touched the bar to to paper clips again, and it picked them up. Some of the iron molecules in the bar had re-aligned themselves along the earth's magnetic field, causing the bar to become a weak magnet.

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Has any one had their compass reverse poles? So a North needle is now South.

Never had it happen to me, but a friend had a compass that was reversed like that. That guy never had any idea where the heck he was unless he was on a road had a dotted line in the middle. :unsure: Not sure if that was the compass' fault, tho. No idea how it happens. It seems like it should take a lot more than "normal" magnetic fields to cause reversal, but...

 

I would prefer not to toss it since I’ve had it for years.

Well, I guess if you're sure you can remember that it's backward, when you're wet, cold, hungry and lost, then it might be OK to keep it. But if you forget and walk a mile in the wrong direction, you might maybe could be a little bit dead before you find your way back. :unsure:

 

I consider my GPS to be a neat techno labor-saving device. My compass is a serious tool that I might need to stay alive someday. The best idea, IMHO, is to toss a bassackward compass in the trash and go buy a better one; then you won't miss the old one.

Edited by Major Catastrophe
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