Why do magnetic compasses spin when in the presence of magnetic rock?

In summary, magnetic compasses spin when in the presence of magnetic rock that contains a high concentration of magnetite. This is due to the constant rotation of the compass's own magnetic field. However, this only occurs when the magnetite is moved in a circular motion around the compass. The popular belief that compasses spin wildly in the presence of magnetite, such as in the Bermuda triangle, is false. In reality, a compass will simply align itself to the surrounding magnetic fields and track them as you move. Therefore, it is important to be aware of the magnetic fields in an area to ensure accurate compass readings.
  • #1
Bararontok
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It has been said that magnetic compasses spin when in the presence of magnetic rock that contains a high concentration of magnetite. But the question is why does this happen? How is the magnetism of the magnetic rock turned by the magnetic compass into rotary mechanical motion?
 
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  • #2
To cause the compass to spin, it would have to be constantly rotating it's own magnetic field - this doesn't happen and so the compass won't spin unless you move the magnetite around the compass in a circular motion.

Here's the wiki on it: http://en.wikipedia.org/wiki/Magnetite
 
  • #3
This proves that the assumptions that the media makes about the behavior of compasses is exaggerated and wrong. This idea was wrong from the beginning but it was advisable to seek confirmation from a reliable source. There are a lot of fictional media circulating around, especially ones about surviving the wild that say that compasses spin when they are in the presence of magnetite and the Bermuda triangle but this is all just modern day popular myth.
 
  • #4
In the presence of a magnetic field, a compass can't be guaranteed to be pointing north.

This is an important fact if you are in an area known for this type of activity. However, a compass isn't going to wildly spin just because it's by a magnetic rock.

To get it to spin, I suppose the simplest way is to have a motor type setup - this would induce the conditions required for the compass to spin.

EDIT: I suppose if you're in an area with a significant magnetic field the compass will align to it and as you move, it will track this field instead (and any surrounding fields) so it could appear to spin as it tracks the various magnetic locations - but you need to note it's not spinning because of the rocks magnetic field, it will only move as and when you move between them (imagine moving a compass around a number of magnets on your desk).
 
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The spinning of a magnetic compass in the presence of magnetic rock can be explained by the principles of electromagnetism. Magnetite, a naturally occurring mineral, has the ability to retain a strong magnetic field. When a magnetic compass is placed near a high concentration of magnetite, the magnetic field of the rock interacts with the magnetic field of the compass needle, causing it to spin.

This is because the compass needle is a small, lightweight magnet with a north and south pole. When placed near a stronger magnet, like magnetite, the needle aligns itself with the magnetic field of the rock. The north pole of the compass needle is attracted to the south pole of the magnetite, causing the needle to point in that direction. As the compass is moved around the rock, the needle will continue to align itself with the changing magnetic field, resulting in a spinning motion.

In terms of how this interaction turns into rotary mechanical motion, it is due to the design of the compass itself. The needle is suspended on a pivot point, allowing it to rotate freely. As the needle aligns with the magnetic field of the rock, it exerts a force on the pivot point, causing the needle to rotate. This rotation is then translated into movement of the compass card, which displays the direction of magnetic north.

In conclusion, the spinning of a magnetic compass in the presence of magnetic rock is a result of the interaction between the magnetic fields of the rock and the compass needle. This phenomenon is a fundamental principle of electromagnetism and has been utilized for centuries in navigation and exploration.
 

FAQ: Why do magnetic compasses spin when in the presence of magnetic rock?

Why do magnetic compasses spin when in the presence of magnetic rock?

Magnetic compasses spin when in the presence of magnetic rock because the rock contains iron minerals that have magnetic properties. These minerals create a magnetic field that can interfere with the Earth's magnetic field, causing the compass needle to spin and point in a different direction.

How does the Earth's magnetic field affect magnetic compasses?

The Earth's magnetic field is created by the movement of molten iron in its core. This magnetic field is what causes magnetic compasses to align with the Earth's north and south poles. When a magnetic compass is near a magnetic rock, the Earth's magnetic field is distorted, causing the compass needle to spin.

Can other objects besides magnetic rocks affect magnetic compasses?

Yes, other objects with strong magnetic fields can also affect magnetic compasses. This includes electronics, power lines, and even large structures made of steel. These objects can cause the compass needle to deflect from its true north-south orientation.

Why do some magnetic rocks have a stronger effect on compasses than others?

The strength of a magnetic field depends on the amount and distribution of iron minerals in the rock. The more iron minerals present, the stronger the magnetic field will be. Additionally, the distance between the compass and the magnetic rock also plays a role in the strength of the effect.

How can I use a magnetic compass near magnetic rocks?

To use a magnetic compass near magnetic rocks, it is important to first identify the direction of true north using a map or GPS. Then, take note of the direction the compass needle is pointing in relation to true north. This will help you adjust for any interference caused by the magnetic rock and still accurately navigate using the compass.

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